Cylinder heads??

Will a 2 1/4 head fit straight on to a 2.5 NA?

If so, would skimming the 2 1/4 head give you more power?

It might "fit" but total destruction is a likely outcome if you try to start it up.

Check all the clearances VERY carefully, and remember the compression ratio will be raised from an already very high 23 to 1 to a bit more than 25 to 1, and that ladies and gents is a lot.

The valves in the 2.25 head are smaller than 2.5 valves, and so on.

In a word .... no.

CHarlesY