71 C20 starting problem

[Bruser]

I need some help with a starting problem with my 71 C20. After I got it back from the body shop it won't crank. Here's a background and list of things I have already tried. History; last May I started tear down to prepare for painting. Everything in the dash came out or loose. Truck was driven daily before this and never had any problems running or starting. It has been converted to Electronic Ignition but other than that it is a stock 350 (a 78 year not the original 71 year). I have replaced the battery, taken the starter to auto electric shop for testing (passed), new battery cables positive and negative, replaced the fuse and holder that is close to the battery coming off junction on inner fender area. Engine is not locked up, I have turned it over at the flywheel and taken all plugs out to reduce compression. Symptoms; engaging starter at key (lock is out) the solenoid clicks and throws starter gear into flywheel enough to barely begin to turn engine over then stops. If I jump the solenoid with a screw driver it turns over like a champ. What gives? Could it be the key switch? The ammeter is not hooked up yet, is this necessary for the circuit. Fusable links?