[Don66GTO]

I have a 66 GTO with a 74 455 from a LeMans with an engine code of YU it also had what appeared to be the numbers 078400 located on the front passenger side of the block. I was wondering if the 4x heads that are on it (the exhaust manifold had 4x stamped into it si I think that it it has 4x heads) are worth the money it would take to get them ported and polished or it I should go in another direction with them.

also do these heads have the d port?

can you get performance heads with the d port or do you have to get the ram air III or IV type heads for making more HP?

I am new to the scene having just purchaced the GTO recently.