GT40 or C9OE

Have a chance to get a set of C9OE heads that have been rebuilt,new seats, valve job.knurled guides etc. for less than freshening up a set of GT40 heads.The question is the combustion chamber is smaller than the GT40's.Will this effect my compression ratio where I will have to use premium gas or have issues with valve to piston clearance.I haven't had the heads off yet so don't know what the pistons look like.I have a late 70's 351 w going into a 56 f-100.Building a driver but don't want a slug.Thanks for any opinions.

 

The late 351 will have dished pistons, CR shouldn't be a problem.

 

The C90E 351W head has a 60cc chamber while the GT40 has a 65cc chamber. They both should have 1.84/1.54 valves, but the ports should be a little better on the GT40

So the C9OE head will raise compression about .75 (if you had 10:1, you would now have 10.75:1)

 

Thanks for the replys.I figured any head will be a improvement over whats on there now.

 

If the c9 heads are from a 302, then they arent going to work on the 351 due to the smaller head bolts. Just keep that in mind.