what ubuntu source version should I use to add some debug prints? (for ubuntu boot-up debug)

I'm trying to install ubuntu 20.04 on my virtual machine (using qemu-5.1.0).
This virtual machine is based on arm/virt machine from qemu and I added a peripheral device and changed the address map according to our SoC being developed. The installation is halted at the early stage so I thought maybe if I rebuild the ubuntu (the linux kernel) with some prints or debug mode and use it for the ubuntu install, I could analyze what is wrong.
The .iso image I used for ubuntu 20.04 is from http://ports.ubuntu.com/ubuntu-ports/dists/focal-updates/main/installer-arm64/current/legacy-images/netboot/mini.iso
and the procedure is based on this web page : https://futurewei-cloud.github.io/ARM-Datacenter/qemu/how-to-launch-aarch64-vm/
The image is installed ok on original 'virt' machine and here is the outcome of the software version :

ckim@virt-ubuntu-20:~$ uname -r
    5.4.0-74-generic
ckim@virt-ubuntu-20:~$ uname -a
    Linux virt-ubuntu-20 5.4.0-74-generic #83-Ubuntu SMP Sat May 8 02:34:05 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
ckim@virt-ubuntu-20:~$ 
ckim@virt-ubuntu-20:~$ lsb_release -a
    No LSB modules are available.
    Distributor ID: Ubuntu
    Description:    Ubuntu 20.04.2 LTS
    Release:    20.04
    Codename:   focal

If I mount the mini.iso file (with -o loop) and see inside, of course there is no linux or ubuntu source I can use to build it anew. So I clone the ubuntu source from http://kernel.ubuntu.com/git/ubuntu/ubuntu-focal.git and did git clone git://kernel.ubuntu.com/ubuntu/ubuntu-focal.git. When I do git tag I can see below tags.

Ubuntu-5.4-5.4.0-10.13
Ubuntu-5.4-5.4.0-11.14
Ubuntu-5.4-5.4.0-12.15
Ubuntu-5.4-5.4.0-13.16
Ubuntu-5.4-5.4.0-14.17
Ubuntu-5.4-5.4.0-15.18
Ubuntu-5.4.0-15.18
Ubuntu-5.4.0-16.19
Ubuntu-5.4.0-17.20
Ubuntu-5.4.0-17.21
Ubuntu-5.4.0-18.22
Ubuntu-5.4.0-19.23
Ubuntu-5.4.0-20.24
Ubuntu-5.4.0-21.25
Ubuntu-5.4.0-22.26
Ubuntu-5.4.0-23.27
Ubuntu-5.4.0-24.28
Ubuntu-5.4.0-25.29
Ubuntu-5.4.0-26.30
Ubuntu-5.4.0-28.32
Ubuntu-5.4.0-29.33
Ubuntu-5.4.0-30.34
Ubuntu-5.4.0-31.35
Ubuntu-5.4.0-32.36
Ubuntu-5.4.0-33.37
Ubuntu-5.4.0-34.38
Ubuntu-5.4.0-37.41
Ubuntu-5.4.0-38.42
Ubuntu-5.4.0-39.43
Ubuntu-5.4.0-40.44
Ubuntu-5.4.0-41.45
Ubuntu-5.4.0-42.46
Ubuntu-5.4.0-43.47
Ubuntu-5.4.0-44.48
Ubuntu-5.4.0-45.49
Ubuntu-5.4.0-46.50
Ubuntu-5.4.0-47.51
Ubuntu-5.4.0-48.52
Ubuntu-5.4.0-49.53
Ubuntu-5.4.0-51.56
Ubuntu-5.4.0-52.57
Ubuntu-5.4.0-53.59
Ubuntu-5.4.0-54.60
Ubuntu-5.4.0-55.61
Ubuntu-5.4.0-56.62
Ubuntu-5.4.0-57.63
Ubuntu-5.4.0-58.64
Ubuntu-5.4.0-59.65
Ubuntu-5.4.0-60.67
Ubuntu-5.4.0-61.69
Ubuntu-5.4.0-62.70
Ubuntu-5.4.0-63.71
Ubuntu-5.4.0-64.72
Ubuntu-5.4.0-65.73
Ubuntu-5.4.0-66.74
Ubuntu-5.4.0-67.75
Ubuntu-5.4.0-68.76
Ubuntu-5.4.0-70.78
Ubuntu-5.4.0-71.79
Ubuntu-5.4.0-72.80
Ubuntu-5.4.0-73.82
Ubuntu-5.4.0-74.83
Ubuntu-5.4.0-75.84
Ubuntu-5.4.0-76.85
Ubuntu-5.4.0-8.11
Ubuntu-5.4.0-9.12
Ubuntu-hwe-5.11-5.11.0-16.17_20.04.2
Ubuntu-hwe-5.11-5.11.0-16.17_20.04.4
Ubuntu-hwe-5.11-5.11.0-16.17_20.04.5
Ubuntu-hwe-5.11-5.11.0-20.21_20.04.1
Ubuntu-hwe-5.8-5.8.0-18.19_20.04.2
Ubuntu-hwe-5.8-5.8.0-18.19_20.04.3
Ubuntu-hwe-5.8-5.8.0-19.20_20.04.1
Ubuntu-hwe-5.8-5.8.0-19.20_20.04.2
Ubuntu-hwe-5.8-5.8.0-19.20_20.04.3
Ubuntu-hwe-5.8-5.8.0-19.20_20.04.4
Ubuntu-hwe-5.8-5.8.0-20.21_20.04.1
Ubuntu-hwe-5.8-5.8.0-21.22_20.04.1
Ubuntu-hwe-5.8-5.8.0-22.23_20.04.1
Ubuntu-hwe-5.8-5.8.0-23.24_20.04.1
Ubuntu-hwe-5.8-5.8.0-25.26_20.04.1
Ubuntu-hwe-5.8-5.8.0-28.30_20.04.1
Ubuntu-hwe-5.8-5.8.0-29.31_20.04.1
Ubuntu-hwe-5.8-5.8.0-30.32_20.04.1
Ubuntu-hwe-5.8-5.8.0-31.33_20.04.1
Ubuntu-hwe-5.8-5.8.0-32.34_20.04.1
Ubuntu-hwe-5.8-5.8.0-33.36_20.04.1
Ubuntu-hwe-5.8-5.8.0-34.37_20.04.1
Ubuntu-hwe-5.8-5.8.0-34.37_20.04.2
Ubuntu-hwe-5.8-5.8.0-36.40_20.04.1
Ubuntu-hwe-5.8-5.8.0-37.42_20.04.1
Ubuntu-hwe-5.8-5.8.0-38.43_20.04.1
Ubuntu-hwe-5.8-5.8.0-39.44_20.04.1
Ubuntu-hwe-5.8-5.8.0-40.45_20.04.1
Ubuntu-hwe-5.8-5.8.0-41.46_20.04.1
Ubuntu-hwe-5.8-5.8.0-42.47_20.04.1
Ubuntu-hwe-5.8-5.8.0-43.49_20.04.1
Ubuntu-hwe-5.8-5.8.0-44.50_20.04.1
Ubuntu-hwe-5.8-5.8.0-45.51_20.04.1
Ubuntu-hwe-5.8-5.8.0-48.54_20.04.1
Ubuntu-hwe-5.8-5.8.0-49.55_20.04.1
Ubuntu-hwe-5.8-5.8.0-50.56_20.04.1
Ubuntu-hwe-5.8-5.8.0-51.57_20.04.1
Ubuntu-hwe-5.8-5.8.0-52.59_20.04.1
Ubuntu-hwe-5.8-5.8.0-53.60_20.04.1
Ubuntu-hwe-5.8-5.8.0-54.61_20.04.1
Ubuntu-hwe-5.8-5.8.0-55.62_20.04.1
Ubuntu-hwe-5.8-5.8.0-56.63_20.04.1
Ubuntu-hwe-5.8-5.8.0-57.64_20.04.1
Ubuntu-raspi-5.4.0-1007.7
Ubuntu-raspi-5.4.0-1008.8
Ubuntu-raspi-5.4.0-1009.9
Ubuntu-raspi2-5.4-5.4.0-1001.1
Ubuntu-raspi2-5.4-5.4.0-1002.2
Ubuntu-raspi2-5.4.0-1003.3
Ubuntu-raspi2-5.4.0-1004.4
Ubuntu-raspi2-5.4.0-1005.5
Ubuntu-raspi2-5.4.0-1006.6
v5.0
v5.11
v5.4
v5.8

To use the matching version with the mini.iso above, what version should I use?
Can I just use 5.4.0-74-83?

You need any distribution of Linux 5.8.0, preferably the newest

Ubuntu 20.04.1 released with 5.4.0, and 20.04.2 released with 5.8.0.

Your image is 20.04.2, as the output in your question suggests.

As for the number after the dash, it refers to different (or updates) distributions of that same kernel, which were paired with the same release, so your best bet is to go with the newest version (regarding the last number only) so you get all of the security upgrades. That said, most of the the newer versions should at least "play nice."

For example, I am running 20.04.2 LTS. Currently, I am on 5.8.0 - 55, even though I installed it months ago, and created the iso thumb drive almost a year ago.