The 1008 is a FelPro head gasket number so that's not related to the pistons. From your cranking pressure, I'd bet you have the stock 2 eyebrow 340 pistons. You gave a lot of good info right off the bat. I commend you for that. Most don't and we have to assume.
Ya, its all speculation unless your the builder, as i bought it as is, much assumption on internals, shop paper doesnt specify parts except "customer supplied" as i believe it was assembled by owner and the info came second hand to me.