1991 360?

The answer to your question is "308" cylinder heads.

They Have Smog Ports.
They have 1.88/1.60 valves.
They have weak springs...only good for .450"ish lift.
They have W2 style raised exhaust port floors.
They already have 7/16" enlarged pushrod holes.

They Flow good.

They tend to crack between the valve seats.

They are "Awesome" heads IF they are in good condition.

Congrats on your Longblock Choice....I run a 89 LA 360....(same thing)