I have a 73 block in a 67 useing 67 mounts and perches.I bolted a strap of iron to the 3 hole block and welded the motor in.Now that im restoring this car I want it done the right way. Can I drill and tap my bosses on the block or should I use adaptor straps? I looked at the straps in classic but don't understand how they work with only 4 holes.