[Christ]

Actually, that last number is wholly incorrect, because I didn't account for throttle position during cruise, and for that, I'd have to know the VE and BSFC of the engine in it's new form to determine approximate torque at X rpm blahblahblah.

Still, I'd put cruise displacement somewhere between .6 and 1.0 (Bigger range, is all.)

Depending on things like piston travel and other factors such as exhaust/intake frequency, it could actually be better to stay at a higher RPM after you've reduced your effective displacement so much.