engine dies

[70-Chevy]

Gentleman (and Ladies),
My dad has a 66 chevy c-10 shortbed that he just put a brand new built 383 stroker motor in. The motor was broke in great and ran great at the start of this project. He had a stock GM HEI distributor with the big volt coil and high performance module installed in the distributor. With this setup it wasnt running bad at all, but it didnt feel like a true 383 should when it came to "pep". So he found a good deal on a brand new msd distributor, #msd-8360 on summitracing.com, and installed that with a high performance stand alone coil that mounts to the firewall. The motor fires right up perfectly when it is jump started, but then after almost exactly a minute, the voltmeter drops from 13 down to complete dead. The motor wont even try to crank and the lights wont even turn on. But as soon as you touch the jumper cables to the battery from another engine, she fires right up to 13 volts.

Now, my father has been over this thing for a month. Hes checked the grounds, he has brand new ground cables in all the right spots. He has checked the proper distributor hook up numerous times. Is there anything else you guys and gals can recommend on why this motor is having this electrical problem. He's mad at the world because he wants to drive and break in this motor completley, but he cant get down the road more than 200 yards. ANY suggestions would be greatly appreciated. I will take your suggestions and talk to him back and forth on this issue. You guys have helped me on issues numerous times before with my truck and I couldnt think of a better place to try to get help for him than here. Thanks in advance!

Chris