If putting an A14 head on an A12 block will lower compression can you put an A12 head on an A14 to increase compression or does it not flow as well so youd be better off with the A14 head?

A12 stock head only goes w/ A12 bottom. A13&14 heads interchange.

try this!
Overbore the A12, fit the A14 pistons to give 1270cc. You'll have to use the A14 gudgeons, and bore the little end out in the rod. I think you skim the top of the pistons too..hmmm???
Skim an oval port head down until you get around 10.5:1 compression. You can take heaps off these...
Plonk in a 280 degree cam, use 32mm chokes in the 42's and shout it headers and a decent exhaust.
It'll make around 100hp at 7000rpm and be the most fun you can have with your pants on!
People wont believe it's not an A14!

if using the gx had on standard 1200 block u might find that the oil pick up for the rockers wont line up as i had this problem simple solution is dril hole in head out to original rocker post gallery