I completely forgot about the intake and exhaust valve diameter differences. I guess that should be a given being that they are two completely differently sized engines. I'm not planning on swapping the heads, yet. I've tried selling them and have had no takers. If I can get them modded to fit the 3400, with larger valves and port/polish I might sometime in the future. I'll get the casting numbers tonight, I keep forgetting to do that. My main goal is explained in this thread:
http://www.aleromod.com/forums/showthread.php?t=25988