Bear this in mind:
When you weld, the weldment itself is stronger than the metal you're welding to- BUT- you also retemper the frame and this is certainly NOT a good thing. This is specifically why you want to minimize welds on load-bearing members, and if you must weld you want to reinforce the joint in such a way as the weld isn't taking the load directly. This is why you sleeve a joint when you weld a rollcage if at all possible.
It's a great build- don't lose sight of doing it right just because you've got some seat time. :)