I'm not sure if this should have gone with the 504/505 mods thread but here goes. The 2.7/2.8 V6 that you talk about - is this the same V6 in Pug 604's.
The 'PRV' bit is this the motor developed in conjunction with Renault and Volvo. Does this mean that if you came across a Renault 30 or a Volvo ____? that everything is the same?
What are the main differences if any?
Does putting the V6 into the 504 stuff up the front/rear weight distribution very much?
Finally is it better to(less expense and complexity) simply modify an injected 2 litre rather than use the V6?
I say this because when I had an injected 504 people got scared when you mentioned anything going wrong with the injector pump (not that anything did!), and old 604's seem to be a dime a dozen at the moment.