We had to use a 2 inch blower belt with our 28 inch rad , dual spal fans and electric water pump because a 3 inch belt would clear on our small block duster.
MRL lifters with the offset pushrod seat should work real well with the W-2 heads, also the pushrod tunnel in the head may have to be opened up to use a 3/8 dia. pushrod.
We installed the Comp Cams solid roller lifters in a 340 block and needed some grinding on the block to clear the lifters and that was all. But MRL Performance sell solid rollers that will drop in with no grinding to the block and have pressure oiling to the roller bearings.
Small block oil pump rotors measure .825 . The big block rotors measure .942 . the recessed pump cover was to install the big block rotors in a small block oil pump.