Trust me, if the #50 and #50 (as they were known in their Uintah days) could handle the 7-1/2% grade and 88' radius of Moro Castle on the Uintah, they could handle anything the Loop threw at them. One possible exception might be the cut between the pin truss and turntable bridges. Locomotive weights, however, is a different matter, and that would require some research into the weight of the locomotives (in their side-tanker configuration) and the capacities of the Loop's bridges.
I honestly can't tell you if it was even the Ashbys intent to use the locomotives on the Loop; they may have had something else in mind.
Mike
Otto Perry photos, DPL collection.
Baxter Pass; Moro Castle curve at the left center of picture:
Climbing the 7% grade with a Shay at the head end:
One of the articulateds entering Moro Castle curve:
Unreconstituted Baldwin narrow-gauge articulated locomotive: