Check to see if you have 12 volts ... going to the distributor ... BUT ... it sounds like ... Low compression ... may be the problem.
With the 283 sitting so long ... the rings may be stuck and the valves may not be seated. Get a compression gauge and check each cylinder ... see if one or more is very low. Sometimes you can squirt some oil into the cylinder with the spark plugs out and get the cylinder sealed up enough to get enough compression for it to start.
Then ... sometimes the cylinder will seal up after running a little and getting up to operating temperature.