dont think he's on any forums mate, but Edition 38 is the best for info and help on any Golf stuff.
Not seen a Mk.4 dash in one , Mk.4 Polo dashes go in tho.
i can remember certain things he got stuck on.
Emerald ECU's make sure its compatible with the immobiliser in the Mk.4 clocks , he managed to bypass that and run it in mk.1 GTI clocks.
Intercoolers, get the best one possible , he used an iveco turbo daily one !!!
Front shockers, due to the extra weight of the engine, he used mk.1 convertible koni's
Drive shafts bending due to the torque !
Only use cable change boxes out of a passat or G60.
But it is one of the most mental things ive been in especially against a bently GT at around 160mph !!!
I used to have a maxed out G60 Mk.2 and top end was very similar, immense torque, miles more than a S3 and a modded subaru . He'll love it to bits !!!
If he does have any queries give us a shout and ill get him to mail ya.