Big Block Gear Drive On A Slant?

Yup. I plan on about a .040" hole in the main oil gallery plug right behind the cam gear. I believe that'll do it.
Do you have the champher on the #1 main bearing? Aftermarket bearing does not have the chamfer. I always chamfer the bearing with a file.
From the factory service manual.

"CRANKSHAFT MAIN BEARINGS The NOS. 1, 2 and 4 lower main bearings are interchangeable (Fig. 41). The NOS. 2 and 4 upper main bearings are interchangeable. The NO. 1 upper main bearing is not interchangeable and is chamfered on the tab side for timing chain oiling and can be identified by a red marking on the edge of the bearing. "