On a 70 340, E body, if it matters, is it right that the either end mounting taps in the heads are the correct locations in these water jacket areas to install the studs, as opposed to bolts? And are conical washers imperative to install on all studs & bolts? Thanks all...

(1) repeat Q #1 again (2) the conical washers/slightly thinner bolts let the manifold expand/contract since it is always heating/cooling so it wont bind and end up cracking. I've used regular washers under a bolt head on a stock car & no probs, not sure on the street if if there'd be a longevity issue somewhere down the line but Ma felt they were neccessary and w the price of those manifolds I'd for sure use em.

I was a bit confused by the way you worded that but re-read it

Do the outer exhaust manifold bolt holes on a small block head go through to the cooling jacket/contact coolant? Yes

The factory installed studs in the outer holes. They used a sleeve like barrel nut on the studs, heres an example Example: stud nut

Personally I would spring for the factory type washers, but you could probably get by without them

All end holes go into water jacket and get a stud and conical washer w/nut. In addition, the passenger side gets 2 more studs on the "second to the end holes" for the long shaft nuts. The other holes just get a bolt with no washers.

Thanks guys!!! I appreciate that!!

Nope. Those are not used on the end studs. Only used on the second from the end studs on the passenger side.