85-308

hi all; newbie here; I have just picked up a 4.2 40v motor to use for 'fitting and measurement' in my project car. The intent right now is to twin turbo it and thus upgrade it to 'mimic' the 473hp versions that came stock from audi.
At this time I am just starting out and so have lots of investigation to do. From what I can see, a long list of 4.2's had 11:1 compression including turbo'd versions. It seems I need to find a list(s) of the technical info on various 4.2's; right now preferably from about 2000 to about 2005.
Can anyone point me in this direction? I HAVE been looking and find conflicting info, much of it due to 'overlap' in years and models so that I don't know which is right (if either).
I'll also be looking into ECM differences etc. I have the ecm that came with the motor and hope I can simply get it reprogrammed...
Appreciate any help.
Email rather than pm me pls; gwpotts5@gmail.com

thanks in advance
GP