273 needs new heads, suggestions

See what casting number your 273 heads are......if they are the correct, earlier castings, they should have a slightly smaller combustion chamber volume than the '68 and up, if I remember correctly. I thought I'd also seen those '64~'67's listed at 55cc's. Got this off the 'net......

Cylinder Heads

Year Engine Service Part # Casting # Combustion Chamber Volume (cc’s)

64-65 *273 *2532080 *2465315 *57.0-64.5
66 *273 *2536176 *2536178 *57.0-64.5
67 *273/318 *2806213 *2658920 *57.0-64.5
68-71 *273/318 *2843674 *2843675 *60.0-67.5