Difference between big block and small block motor mount perches???

[FLYNAVY30]

I just ordered my LS swap kit from BRP Muscle Rods.....


My question is, do I need to order the small block frame perches because it appears that my factory big block has 4 bolts as opposed to the single bolt mounting you can see in this kit.....or do the supplied brackets mount directly to the frame with a single bolt, eliminating the factory perches? Unfortunately the included directions arent terribly precise.

Yes the kit is meant for a half ton truck, but nobody makes an LS kit specifically for the 3/4 tons.

Thanks