Update from this weekend's efforts - I dropped the pan again and the plastic tray had several gouges, which is pretty much as I expected. I got a new tray from Jegs to fit for a 4.15" stroker crank. Mocking it up showed that it had plenty of extra clearance so good to go. Firing the motor up afterwards had good results and no more drumming from the bottom end. The rear main seal issue was corrected by removing the billet aftermarket unit and putting the factory style back in...no more leaks! I took some pictures of the rod hardware but I have no idea if the bolts are stock or aftermarket. The motor was built about 33 years ago so not sure what was available back then. I wonder if this might be more of a Hemi issue since never had it on any 440 previously.

68jim