1994 Other Mitsubishi Models won't start timing belt or what

I assume the heads were rebuilt by a reliable shop and you checked the rings before re installing the heads. If yes to both I'd assume your valve timing is off. Rotate the engine until the Top Dead Center marks are where they are supposed to be and if you are off even a tooth or two, (i.E. The markers are close but not dead nuts on), your compression readings will be all over the board. A good idea is to rotate the engine by hand a couple of complete revolutions and re align the timing marks before re installing the timing gear components just to make sure you are on the money valve timing wise