The D-model?
FL200-250, 275 KTAS, Down low, FL100, 285 KTAS, two engine obviously.
The aircraft does very well on one engine for a turboprop, makes the required climb gradient in many obstacle ridden mountainous airports on one donk. At medium weights the "OEI net climb gradient" hart shows a positive slope as high as 16,000 feet. That can sag as low as 12-13,000 at max weight, warm temps aloft, and engine anti-ice on. If i recall correctly anti-ice resulted in a 2000 foot hit, or thereabouts. We had a driftdown program to operate over the Rockies at max weights over the most challenging routes.
I don't have the charts handy, but I think you could do about 190-200 KTAS single engine.