Run what you brung. I am doing my black badge course this weekend with an old 1911 a1. Built in 1943. Dinky sghts and shoots about 5 inches at 25 yards. For the ranges that they shoot at it should be fine.
I had a ruger p-85 mk 2. It shot much better than my old 45. The only hinderance is that the 9 mm will be classified as a minor caliber. The only difference that I can see just reading the regs is a bullseye is scored as 5 for major and 5 for minor. However the next score level outside of the bull is 4 for minor and 5 for major.
So If you can shoot straight it should'nt matter a great deal. If you are looking to spend some money you might need to get a few mag pouches.
A long match requires 32 bullets.