Ok, I have a 94 Mitsu Galant GS that comes stock with a 4G64 DOHC rated at 160hp with a 10:1 CR. I had a freak accident with the crank pulley and currectly replacing the cylinder head. The cylinder head comes from a 4G67, an 1.8L DOHC from the 92-95 Hyundai Elantra GLS, which is like the 91-94 Eclipse cylinder head but with a smaller combustion chamber: 43cc.  Once install, the compression ration will range somewhere between 10.4 to 10.6. My question is what course of action should be taken to prevent detonation/knock: upgrade fuel pump, slightly larger fuel injectors, fuel pressure regulator, retard timing, iridium spark plugs, 100 octane fuel, etc?  

chances are nothing too much will happen, but if you are expierencing knocking use 91 if you live in cali or 93 for the rest of the country(I know you can get higher in some places). If that doesn't work retard the timing a little bit, and if that fails remap ecu.  

What may be of more importance is the included valve angles, lift, and other crit dimensions. I'm not familliar with specs on either engine you're using, but metal to metal contact is far more serious than knock.  Skip all that crap and just throw a 4g63t in there!