I'm installing a MSD Start retard this evening in my 496. I locked the distributor and will be running 37 degrees timing.I thought the retard could be set for 20 degrees but it only has 10 and 25 as options.Should I set the retard up for 10 or 25 degrees start retard and is it better to hook the retard up to the starter or set it up so it stays retarded until approx. 1300 RPM . The motor is 13:1 and the cam has .782/.72 gross lift w/ duration @ .05 of 289/289. Currently I'm starting O.K. and idling O.K.@ 1100 RPM with 20 degrees of advance.