With the slicks, you probably won't see much gains with the a locking diff. The stock diff will even distribute to both wheels, so long as neither is slipping. With slicks you should ideally have no slippage on launch.
There is of course the issue of not getting both to burnout well with the stock diff. But I'm not sure your 60' would suffer much from having on cold slick.
An LSD won't hurt, but it may not be the greatest return on the dollar to E.T. ratio.
Porting the IM, however, yeah..... You're gonna wanna do that.