[Christ]

These are made using 205/75R14 tires, a PT Cruiser transmission, and assuming a 3500 RPM redline, but the redline of Cara's donor engine is more like 3000.

RPM.....MPH
3500...85.07
3000...72.92
2500...60.77
2000...48.61
1500...36.46
1000...24.31

Gear ratios
1st.................3.500
2nd................1.960
3rd.................1.360
4th.................0.971
5th.................0.811
Final drive ratio 3.940

The engine makes peak torque around 2000 RPM (all 75lb ft) and peak HP at like 3000 RPM (screaming 40 HP)

I don't usually go over 60 MPH, and a good bit of my driving is @ 50-55 MPH.

Does this seem like it would work out, or should I use something with longer gears, like a 3.55 final ratio?

With a 3.55 and the same tires, I get the following RPM/Speed:

RPM......MPH
3500.....94.42
3000.....80.93
2500.....67.44
2000.....53.95
1500.....40.46
1000.....26.98

If you'd like to consider aerodynamics before answering, the current numbers for Cara are 3500lbs, .35Cd, and 35FT^2 frontal area. (Yeah, it seems weird, but they're the numbers I've got.)