It's a pain to get in there when it's all assembled, but I've always tightened the block side motor mount bolts after I set the engine in. It is possible to tilt/adjust/wiggle the engine before fully seating the mounts with most of the weight still supported by the hoist. You may need a crow bar or something similar to help position it. If it's causing a clearance issue on one side, pull up on the hoist a bit and try to pry that side up. It may also help to reposition the hook by a chain link (if not using a plate) to support more weight on the side with clearance issues before re-lowering.
