The Cam's Lift doesn't figure into Stall or Cruise rpm, the Cam's Duration & Operating Range will.
What is your Cam's specs, Part#? Duration @.050 Lift?
At 65mph = 3300rpm if you had a Lockup TC/TorqueConverter, add about 200-300rpm for TC slippage, so 3500-3600rpm @65mph.
245/40/17 Tire is 24.70" Tall
TH350 Gears:
1st = 2.52
2nd = 1.52
3rd = 1.00
A MPH Calculator from RPM and Gearing >> http://hotrodworks.net/hotrodmath/quarter.html
Gear/MPH Calculator >> http://www.f-body.org/gears/
A TH2004R would be a better option for crusing. It's .67/4th Gear and Lockup TC would drop the cruise RPM down to 2200rpm @65mph.
TH2004R Gears:
1st = 2.74
2nd = 1.57
3rd = 1.00
4th = 0.67