The MKIII Supras are notorious heagasket eaters like everyone has said, but they are all missing a key element here. The bottom end is cast iron and the head is aluminium, so when most people do repair jobs like decking the head and block they dont get the right RA finish on it. Much like sand paper the RA number is smoother the lower the numeric is and the MKIII's require an extremely low/smooth RA finish, other wise the head moves the gasket and block eats the headgasket even on stock boost. While ARPs and a copper headgasket ( not recommended) is a quick fix or even an MLS gasket it wont last long. My suggestion would be to go talk to Mike Phillips at Phillips racing engine in Grove City and see what he recommends, they do quite a few import motors and even some of my personal things.