Just bought everything for 3.73 gears

Going off that calculator -

Automatic
in drive gear
3.91 gears since 3.73 isn't an option

29% throttle
75% converter efficiency
71mph = 4189rpm
YIKES!

24% throttle
75%
60mph = 3555rpm
Not as bad but still not good

I drive 30 minutes to work one way, it has a good cooling system, but I can't see it liking that kind of rpm for long...

Well we'll see I guess somewhere between 3,500 and 4,000 cruising rpm is my guess for 70mph