That's not too difficult to reach.
Get your compression up over 10:1, put some decent heads on it that have 180+ intake runner volume, 1-5/8" minimum exhaust headers, a fuel delivery system that moves at least 600-650 cfm, and call a cam manufacturer for a recommendation based on your application.
That should get 350 hp easy.
Chevy used to make a 427 big block, but the 427 small blocks are made from aftermarket parts.
No, the Chevy 454 has a long stoke and requires a big block. However, it is possible to build a 454 small block using aftermarket parts. You'll need some high flowing heads to make it work.
When building a small block chevy engine, you need to decide what exactly you want to do. Restoration or performance enhancement. Normally, the small block chevy engines are harder to build if you want to conserve your cost. Most people try to use aftermarket parts to make it cheaper. Many people have found the book "How to hot rod your small block chevy" to be very helpful. Also, parts suppliers such as Summit and Jeg's have a wealth of information in their catalogs.
No. The 327, is a small block.
Use it to anchor your boat. That motor was such a mistake, I do not even think they make parts for it.
Yes, beginning in 1977.
bore and stroke a chevy 400 smallblock.
No, they did not. The smallest big block Chevy is the 396. They also made a small block and big block 400.
355.
Go to a parts house or bookstore and buy a Haynes Manual that is specific to your car. It will be the best investment you could make as far as repair is concerned.
A small block Chevy has a 4inch bore. When you bore one 30 what you are doing is removing .30 thousandths from the cylinder. That would make the bore 4.030 or turn a 350cid into a 355cid.
Sounds like an exhaust leak.