As racerone asks, what is wrong with your coil? Did it fail ohm testing?
I haven't tried using a newer coil as a replacement for a discontinued one but the coils for the older 15 and 20 horsepower have been discontinued too. I tell you this because I own a 20D and have a late edition shop manual that lists the resistance values for the coil and I see nothing to indicate that those values have changed from the previous models.
Having said that I can only tell you that, if it were me, I wouldn't hesitate to try the "later" part numbered coil. But ONLY if I had first tested and confirmed my old coil had failed. Then, it would still be a bit of a gamble but one that I would be willing to try.
Not the answer you wanted, I know, but that's the only one I can give.
Good luck and please update with what you decide to do.