If it doesn't spark and run by hot wire, the coil is no good or the points condenser is bad. Again this is assuming the points are installed correctly. Inside the distributer, there is a black wire that comes from the coil. You need to check that wire to make sure it is not broken anywhere. You can do this with your ohm meter. If that wire is good and hot wiring it did not work then the coil HAS to be bad.
Have you done a compression test on the engine? This would tell you if you have stuck valves or a timing chain problem. It would be a good idea to know this before trying to run the engine to avoid doing any further damage if it is out of time.
If that were my truck I would pull the intake, heads and timing chain and inspect everything before trying to get it to run. Those old 283 engines are getting hard to find and I wouldn't risk ruining it.
