Not knowing how old the engine is, that 6 degrees may be OK or it may be too advanced for today's petrol. If in doubt, and yes this is a noisy thing to do, get it warm then wind up the tickover till all the advance is in, then loosen off and rotate the dizzy until you get the highest revs. I do my B series BMC engine at peak torque revs which from memory is about 3500 revs. Then tighten it up.
Alternatively the old school way is to run the car up and down a straight empty road, from one fixed spot to another fixed spot, accelerating from about 20 to 50 in top gear, if you can., (Choose speeds that will make the engine rev from low down the range to quite a bit further up) using a stop watch, or better still getting someone else to do it. Altering the position of the dizzy. The faster the acceleration, i.e. the shorter the time it takes to get from 20 to 50, or whatever, the better the engine is timed.