Re: need mech. adv. springs (they're broken)
If you cannot finf a shop to check the advance curve, how hard would it be to install the springs yourself and then check the curve? How I would do this is at 500 or even 1000 rpm increments check the timing, maybe up to 3500 rpm, note the advance and then plot it on a graph versus rpm. You would need to know what the specs are to compare, and getting that information may be the hardest part. So if you find the right spring, do this little test to ensure it is the correct one. That is all a distributor shop would do.
Have a great day,
Rob.