I know what you mean by being able to get more torque on the screw. You really cant tighten it much with the little bitty allen wrench it takes.I went and got a cap head screw, same thread size.
I had to enlarge the opening a little so the cap head screw could be counter sunk properly.
The cap head let me use a larger allen wrench so I could put more torque on the screw, with blue loctite, never had a problem.
Roll pin also sounds like a good idea