If you have a 3.08 rear you won't have much use for an overdrive the engine will lug when it's in overdrive.The overdrive would be better with 3.55 gears or more,with 4.10's and a 700R4 I was turning around 2400 at 70 MPH.In your Nova the 200R4 would be a better fit,here is a converter
Oregon Performance Transmission - Rebuild Parts for 700R4 4L60E 4L80E E4OD 4R100 47RE 48RE & More GM 200-4R EARLY 27 SPLINE 700R4 HEAVY DUTY HIGH STALL 2000-2600 RPM better to have the lock up with overdrive.In either case your donor overdrive should be from 1987-92 these were non-computer and had the newer upgrades.