How do I download a specific version of build-essentials and dependencies that is not in my native machine

I have Jammy and the version of build-essential I want was the one released for Buster

Here is what I attempted to do:I went to https://gist.github.com/ishad0w/6ce1eb569c734880200c47923577426a and added a new file called sources.list in /etc/apt to add in the new sources so that apt can search here for buster packages

Then I tried:

aptitude --download-only install build-essential=version

but it is not able to find that version (without specifying a version, the default build-essential for jammy is installed. When I went to https://packages.debian.org/search?suite=buster&searchon=names&keywords=build-essential I was able to find it is 12.6, but

 aptitude --download-only install build-essential=12.6 

didn't find any packages with that version:

Unable to find a version "12.6" for the package "build-essential"Unable to apply some actions, aborting

How do I find what the build-essential version is for buster, so I can download its deb and dependencies to my machine?