318 piston questions

I would have your shop order up and use Keith Black hypereutechtic pistons. They are roughly $250/set, but they will give you much better compression. Your factory ones (and the replacements) are not performance parts..They actually yeild around 7.5:1 when installed as the factory did. The newer design raises the top of the piston to very close to the top of the block. Depending on heads and gaskets,. you will end up with a compression around 9:1, maybe a touch more. This will give only benefits even when using a 2bbl. The downside is the cost, and also that the new pistons will need to be balanced. if the budget is firm, then just use his pistons, the price is reasonable, and many shops will not stand by anything if you supply the parts because they did not get them.