How Much Boost for Cast Iron Internals?

Correct. A/F Wide band is mandatory. Rich is better then lean. use a vac distributor and plum it to manifold vac. you don't want it to advance under boost or BANG. Head gaskets will be the first to go. I would not go over 5 lbs boost with a stock motor in new condition with a great tune up and a solid fuel delivery. With Head studs and boost style head gaskets 7-8 psi. with meth injection you can go a little more. any time you boost on a stock motor stuff can go wrong. it will find a weak link. just a little advice from my check book. all this advice is on the cheap build. more money the better the system. boost a older motor and you will wipe out the ring's or worse. Hope this helps. Good luck and have fun