67 valiant redo

What are those bosses used for on the side of the block near the very front?....utilizing the threaded bosses would provide a better / direct shot to the perch.

I'm thinking you mean the holes I put arrows next to:
driver mount holes.jpg

I was considering those, but they are used for the accessory drive mounting I wanted(f-body accessories). Some other accessory drive options likely wouldn't use them.

f-body alternator location:
fbody alternator mount.jpg