actually i'm thinking 4th or 5th gear from a 6speed manual tranny.
from the LITTLE research i've done
3rd gear is like 1.43 and 4th is like 1.2 seems like a good range
3500rpm= 2400 prop rpm
or at 1.2 3250 rpm = 2700 prop rpm.

now wouldn't the prop vibs be less than the abuse the average tranny
takes from a daily drive ?