383 Build - Help!

I did not see an HP on the heads but I could have completely missed it.
Just by looking at the exhaust valves, is it possible to tell?
It does not appear to have any room for a larger valve.

I looked at the heads again and they looked like they have been milled, unless they look that way from the factory.

I have a set of 452 heads that need work but wouldn't that raise the comp too high?

So someone drilled the pistons to balance them, but could have easily not gaped the rings.
They are stamped 040 on the bottom.

I have a 750 Holley that I rebuilt and ran on the car. The thing actually ran better with the t-ram, quieter, more responsive on the highway, and more fun. Not that it has any bearing on this engine. I'd still like to use it though.
It appears the variables that I need to figure out, I have no way of determining most.
The head cc's, if they were milled and to what, the piston height?

I really appreciate everyone's input, but it is a double edged sword so to speak. That's part of the learning process, getting completely confused along the way but to get this right I really need someone local who knows what the heck they are talking about and will also not screw me over.

This thread is not over until I am doing burnouts, and sooner than later.