383 power upgrade help

Afford the best cylinder head you can and top it with a rpm intake (For the street) and a 750, add headers.

Where do your pistons sit in the cylinder? How far down? This is a key item to know. This could help guide you to the heads cc chamber amount.

Your bore size maybe a limitation to valve size.

That and welcome aboard!
Thank you I'm happy to be here could you tell me how I'd go about checking how fat they sit do I just use a regular tape or something special I have a picture of the pistons sitting in the cylinder if that would do any help