Isn't oddesa cylinder head that ebay company?? I've heard bad things about their work. Below is an example from someone that bought their chevy vortec heads.
OP, look into engine quest cylinder heads. Supposed to be quality. Only problem with magnum heads that are seasoned is the things crack so easily. They're kinda junk, leave em on trucks in junk yards IMO. And believe me I looked into them, had three good magnum motors to take heads from, 1 head wasn't cracked of the 6.