Dave:
Here's engine rpm data based on your combination:
3.73 Rear End Gear Ratio
27.5 Effective Tire Diameter
1.0 Transmission High Gear Ratio
55 mph = 2500 RPM
60 mph = 2750 RPM
65 mph = 2950 RPM
70 mph = 3200 RPM
75 mph = 3400 RPM
Note that actual rpm's will be slightly higher due to torque converter slippage.
