Usually people run porsch 944 timing belts with the 16v head, not entirely sure if it transfers o the 20v but anything with the correct amount of teeth will work. Theres a crap load of info on specialist websites that people have built these engines.
Basically if your building one, use forged rods, and if 16v head use 4agze pistons and if 20v use 20v pistons. don't need to do anything to the block. If you retain the standard rods don't go over 6000RPM, you are sure to snap a rod, if you run forged items be happy with 8-9 grand depending on choice of head and cams etc.
Seeing as I'm turbo, if i did build up an eninge id run a bigport 4AGZE head with the GZE pistons and spool rods, that would make an engine that could handle 20psi all day everyday :bash:
Karl.