This will be real hard to comment on without seeing it... any way you could get some pictures? Then I'm sure a number of the experts here could help you out a lot better. If it is a front steer, that means a later front suspension probably, but that does not necessarily mean a bad thing. Are you planning on keeping it as a pro streeter or looking to go back to stock? The later front will have the taller spindles among other goodies to help handle better.
I would NOT cut the control arms and re-weld, very dangerous! If it is a later model suspension, then the frame rails are wider than your stock subframe would have been, so that is where you are getting the increased width. If it really bothers you, you should look for a new front subframe that would be correct for your year, like a 67-69 Camaro/firebird or 68-72 Nova.
Colorado Springs, CO
68 Camaro... someday!
71 Chevelle SS