So if this is a 95bhp engine, then I take it that's one with the "split-lobe" cams (adjust clearance with allen key) rather that the later single lobe design?
You might find better luck asking on the Sprintformation mailing list or the Alfa Pages (for Alfa 33) message board:
http://autos.groups.yahoo.com/group/sprintformation/
http://www.alfa-pages.co.uk/phpbb2/index.php
Or you could try the New Zealand Alfa Romeo Trofeo series pages:
http://groups.msn.com/alfaromeotrofeoseries/
The choice of cam might depend on those pistons you mentioned. The really high lift, long duration cams tend to need valve cut-outs in the pistons.