The heads are off, swap them or not..

They're stated to have around 57cc chambers according to my research, with most other heads being 67cc or larger. These are '67 920 heads. The 318 heads I have state that they're a 63cc chamber I think, but guys say they CC around 65-68cc on average. I'm not sure how much better non magnum 318 heads would flow, the heads I have look identical aside from the chamber. I may even do the porting myself since this is a low buck non permanent engine. Valve springs should be here today and I'm going to try to take the heads for their machine work tomorrow so hopefully we'll know how they do before too long. I just hope I don't have to invest too much in the 273 heads since they need a full rebuild.

I'm assuming I'll just need to do new guides, hardened seats, milling, valve job, plus seals and I guess I'll go ahead and do new locks plus the comp 901 springs.