torque converter problem

I have a 350 engine with a 350 tranny. I bought a torque converter from a friend to save money till I can get one tailored to my specs. When I put the tranny on I noticed that the mounts on the converter went all the way to the edge of the flexplate.(its a 12 3/4" flexplate) The bolt circle on the converter matched the flexplate perfectly. Can these be trimmed back or will it mess up the balancing?