I used Felco intake gaskets. I ran RTV along the front and rear block running it a little up onto the heads covering the end of the gaskets to make sure the seam between the head and block was sealed. Use a bead 1/8" to 3/16" high, you don't want any RTV to get indise the rngine. I used no sealer or adhesive on the gaskets themselves. I used Mike Mavrigian's "How to rebuild a LT1/LT4" along with the GM factory manual. Both said no sealant on the gaskets, only use RTV on the block. Did you use thread sealer on the bolts? They run into the oil galleries and need to be sealed. Torque the bolts in the proper sequence first pass to 71 in lbs and a final pass to 35 ft lbs. Make sure all mating surfaces are clean and dry before you put the gasket or RTV on. We used a lot of asitone to clean surfaces.