360 BALANCING

Ok 360s are externaly balanced and 340, 318s are internaly balanced correct ? I finaly took my barracuda out for a test drive that has a 360 with a super charger. I didnt go over 3000 rpms. I went for about a mile and then came back and check the timing since it was up to temp. Took it back out and did another mile. On the wy back i decided to get on it alittle more from a rolling start. I heard this awful grinding skweeling noise coming from the engine bellhousing area. So i took it easy the rest of the way. When ever i would give it around 1500-2000 rpms it make that noise. My thinking was the throwout bearing. I couldnt sleep that night and i got to thinking. 360s are externaly balanced and i put on a wide spacer and the pully for the super charger on the crank pully. Did i just spin a bearing because its now out of balance ? I closed the garage door and never looked back. Either way i going to sell the super charger and everthing i have for it because that extra weight cant be good for a externaly balanced engine. Ant thoughts ?