Very mild 318 - Comp 252H vs 340 cam?

Good questions - 904 auto with stock converter, '69 Barracuda. I'm unsure of the rear end gearing, but it's a 7.25 so I will probably be trying to find an 8.75 to swap out at some point soon anyway.
Tires are F70-14 Polyglass.
Do you have a tach? If so, what is your RPM at 60MPH?