[C-Leigh Racing]

As long as the outer edge of the squish area matches up to the bore of the cylinder, that dome can be used. If not, then all it needs is for the squish area to be re-machined to match the bore.

Another thing you might want to think about, the OEM TRX cylinders sleeved out to a big bore, can be problematic keeping the head gasket area sealed when using just a gasket, so you might want to think about having the cool head machined so that o rings can be used instead of a gasket.
I will say, I've ran the OEM TRX cylinder big bores & used the gasket, but used Three Bond #1211 sealant on the gasket & allowed several days for the sealant to cure out before finishing the engine build.
Neil

 

[C-Leigh Racing]

I think having a new dome cut, is the best way to go as well.
Because if you start machining on the old cool head dome, to get the CCs right for the 72 piston, it will probably cause the dome to be weak & could crack.
The cool head domes, has those fins machined into the outer part of the dome, so it dont take a lot of dishing out of the bowl area to weaken those domes.
Neil