[fastd]

I actually prefer the .82 5th gear; and your 3:31 rear gear sounds like it would be a good match. The KC 427w should actually be a delightful set up. Maybe you should think about changing the cam.

What kind of horsepower and torque are you putting out? It would be helpful to have it dynoed so we can see you power curves.

What kind of power are you shooting for? I would think you can easily get 450-500 hp out of your current setup. I personally would not like to go to 3.73 from a 3.31 and 2700 rpm at 70 is closer to ideal than 2000 rpm. If you are driving long highway distances I can see you wanting to bring it down to 2200-2300 but not lower.

If you want to go to big block than go for it but you have a great setup currently imo.