How to do an engine assessment on my wifes 81A?

[38 coupe]

Sounds like you have the 39 and later crankshaft. We did a long thread on engine IDs a while back. Check it out: https://www.fordbarn.com/forum/showth...5301&showall=1

If it was me I'd find another car head so you have matching car heads. You will get a little bit better performance and gas mileage. I personally prefer cast iron heads to aluminum since you don't have the corrosion issues with cast iron.