Do a turbo then. STSturbo does the rear mounted turbo setups. Run it with a small amount of boost, say 5-7 psi, then when you rebuild, crank it up higher. But in reality, you are probably better off saving your money towards rebuilding the motor itself. You can buy the goodies now that you'll reuse like carb, intake, headers, aluminum heads, etc so that when rebuild time comes, it's easier on the wallet.