I smoke pheasant breasts all the time (very low in fat and great taste).
I smoke mine around 275. It doesn't take long to cook full breasts let alone pieces. I would say depending on how thick the breasts are I would go a half hour and take a look. Just keep an eye on them. Pheasant is unforgivable if over cooked.
I never probe my meat. If I think it's done I find the thickest piece and cut into it. If its cooked then so are the rest. Whatever you do, don't turn your back on it.
22.5" WSM, 22.5" Weber Kettle, Kenmore 6 burner Gas Grill.....Where's The Beef?