the "cracked" ones are fine to run, they never leak water where they crack between the seats, might be able to get some for really cheap, and they flow better than a 360 head, but with a small chamber for compression. 1.6 ratio rockers also give you more lift/flow out of the cam.
IIRC 20 years ago I found a potential "cheap" performance spring for them, the stock springs out of a GM 3400.
More Information for MELLING VS2224. uses an 8mm valve, IIRC you're limited to about .480" lift....