If you have the stock springs take them to the hardware store and look through the springs there. Find one that size. Might be a couple bucks.
If your stock springs are won't snap the weights shut then take one spring and clip off the loop that hooks it on, bend up the next turn of the spring for a loop. If it is still still not snaping back, clip the other.
Once you get the weight to snap back, check the advance by shooting the timing light at the marks, rev engine. Pay attention to the rmps when the advance stops.
Should hit max advance at 3200 rpms.
If it won't go full at 3200 rpms then springs to tight, stretch them a bit, one at a time, recheck.
If it hits full at less than 3200 spring weak, clip another loop. One at a time recheck.
May take a few tries but worth the effort.
Leo