If you are in the market for an upgrade check this out
White Performance Detail Description
You just cant beat the value, they are easy to set up as well. Make sure you have firewall clearance. Lifetime warranty, 50 bucks, it is a no brainer.
Use it with this limiter plate, limit vacuum adv to 12-14 advance. The unit will add approx 20 deg vacuum advance out of the box, too much
Crane Cams 99619-1 - Crane Vacuum Timing Limiter Plates - Overview - SummitRacing.com
Try it at about 16-20 deg BTDC as the initial and 32-36 total. Use a simple 6/32 screw/nut with some lock tight to limit the mech advance on the HEI rotor plate, the hole is already drilled. The unit will have about 24 deg mechanical advance out of the box, too much.
Give it constant 12V from 15A fused 12 gage feed with toggle switch on dash or elsewhere within reach from driving position.