I have done it myself, had a set of 781 GM ovals with a team g intake "oval", pulled engine out of car to put rear main seal in. Hoist hooked to carb pad and cracked about 1" under carb pad.......... Had a team g square port on the shelf with a set of gaskets, I wanted to go racing that coming weekend so I put it on. The car did pick up from 6.09 to 6.04. Cant swear the intake done it, but Im sure it wasent the rear main seal.