Distributor springs

Try this. Summit Racing® YH and YT Series Advance Curve Kits SUM-850535-1

It's Summit's version of advance springs and advance sticks for the YT series distributors with slightly different advance curves than the Mallory kit that has been discontinued.

If you click on the Instructions just below the overview tab you can download a PDF with the advance curves their springs in the kit will get you.

I used it on my Mopar Performance distributor and it worked great.