Hello mr-mac, good to see you in more friendly surroundings!
I read somewhere the factory was considering in 2002/03 a 156 GTAm version, with an uprated 3.5 Busso V6. Apparantly that was as far they were prepared to go with the block. So perhaps 3.8 is possible but only with considerable expertise and investment?
Either way 3.2 would do me!