2.7 heads vs 2.4 better, worse the same?

[hushpuppy]

Hi,
I'm building a 2.2 displacement engine for my vintage 66 911. I have 2.2 S P&Cs, 66mm counter balanced crank, GE-40 cams, Webber 40 ida 32mm venturi carbs, 5R case with timeserts, oil pressure bypass update. I have a ready to go set of 76 2.7 heads.My question is: do 2.7 heads have the same dome as 2.4 or would they lower or raise or not affect the compression ratio. The 2.2 barrels fit right in the heads, not problem on the OD. Or should I find some 2.2/2.4 heads from 71 to 73. Any other comments on this engine concept would be appreciated. thanks for your service to our Porsche community,

[Flat6pac]

The year of the heads dont make any difference as they all do the same thing.
Volume is all the samein the dome.
Bruce

[914/6]

2.7 heads are chamfered for the bigger bore 90mm 2.2 and 2.4 have 84mm, Yes the chambers do have the same shape. except for 2.0's