My guess is that the ballistics probably wouldn't be very satisfactory for coyotes - at least by present standards. I'm not real familiar with that caliber, but it sounds like it was originally designed for 20 grains of black powder, which would not do very well at 200 yards - and even 100 might be stretching it.
If I were going to shoot it at all, I'd first have it checked out by a competent gunsmith.

Good Luck,
IM jaybe