Re: 462624 head casting any good?
Right; they are among the very worst.
1.94" / 1.50" is the stock valve sizes for the majority of 350 heads. Nothing special about that at all.
They can be made to flow OK, they can even have 2.02" intakes and 1.6" exhausts installed in them. However, one of the things that a flow bench WON'T tell you, is that they'll crack between the valve seats if you enlarge the valves (they're bad enough about that with what comes in them). Furthermore, there's some places that get REAL thin in the exhaust ports, that will also crack if they're ported.
They are trash. Throw them there and get something decent.
Numquam ponenda est pluralitas sine necessitate.
— William of Ockham, c. 1330 AD, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.