65 Barracuda Casting Numbers

On a 65 Barracuda i purchased i had a 273 cammando and a formula S car by the badges but had to use a bore scope (Harbor Freight) to identify the pistons. Without taking a head off. The high performance 273 has two valve reliefs in the piston tops and the 2 barrel has four.
EDIT: I found the 273 was a 2 barrel engine. I have a HP 273 waiting for it.