I would mount the scope on the A3 rifle, not the A2.
I'd only mount an M203 under there, but that's not what you have.
If you must mount that tube under there, go for the A2 and put a USGI forward stock on it as well as the M203 sight on the carry handle so noobs can think you have something kewl.
Thanks for the input guys. I'll post pics when they get finished.
Make it look like this:
Pure SWEETNESS!
Dang Carl. Now I'm going to have to re-do it!