There's more choice of wheels, but that's it really. You want to be looking for bits off an E36 Compact 318ti for the back which would bolt right on to an E30 chassis. The front you could use any E36 bits if you've not yet had your E30 suspension modded yet - you could get them to supply the bit need for an E36 front end. Anything off a 328i will give you some decent size brakes.
Some info from Richard's 328 Compact build:
http://328compact.co.uk/brakes-front
http://328compact.co.uk/brakes-rear