I dunno... the LT1 and Lt4 intake Gaskets are different. I'm sure there is a reason for that.

 

like 2 years ago a buddy of mine bought a lt4 intake from summit and i told him it wouldn't fit without lt4 heads and my brother had a built lt1 without an intake on it so we tried and it won't fit without some machining ! the angle between the heads are different that may be some of the increase in port lenghts !