Fins? Here's what your engine looks like with all the cooling tin removed. Each piston cylinder has steel fins around it (probably rusty) and the heads have fins but are silver aluminum. If the car sat for a long time mice like to build nests above the cylinder tins disrupting airflow and causing a stink!
I don't see any of the '73 California smog stuff on the engine. Transaxle is a '73.
On an engine that you don't know anything about - a compression test is always good for establishing a baseline condition. Low compression or uneven cylinder compression can indicate worn cylinders/rings, bad valves or cylinder-head leaks.