Really excited to see this thread! @Jayhawk500 personally I would sacrifice some torque for a bigger flywheel (or ANY flywheel), since I don't believe these Mohawks have back-drivable gears. So I would use a shorter Pittman 9432, especially if you can find one with two shafts. I believe the MTH Premier 2-8-0's use a single-shaft version of this motor. Also check popular auction sites.
Note the lack of coasting isn't as much of a deal-breaker unless you're also planning to groove the wheels for rubber tires. In that case careless use of the direction button amounts to a literal train wreck!!