Car won't crank, Fusible link blown

The alternator should not be in the circuit when jumpered as we talked. If the battery won't run it the battery is dead or defective. With a decent battery and no lights (daytime) you should be able to run that car for many many miles "off the battery." The ignition system, by itself, probably draws less than 5A

"Back in the 70's" my RR developed an overcharging problem. We were going back to Miramar (San Diego) from Vegas. I pulled the VR connector loose, and we drove that thing hundreds of miles on the battery with no charging system.

Yeh......that's right!! I'm old!!