LA 318 advice

Whatever the actual deck height dimension is for the block being used doesn’t really matter…………. As I said, if I was going to the trouble of decking it to use with cheaper/lower ch pistons…….. I’d deck it enough to get real close to having the deck clearance be about .030 down the hole.
Whether that means cutting it .030, or .050, or whatever.

However, I wouldn’t do any of that if the target for the end result is under 300hp.
That would get what I said earlier……….re-ring, go thru heads, done.