Starting for the 65' Stang for the 1st time this spring... it was dead as my son left the lights on without me knowing! Heh...
But trying to start it after it being on the charger.... BUZZZZZZZZZ.... tried it a couple more times until nothing not even a buzz.... uh oh... figured I may have fried the starter solenoid so I went and got another... yep.. sure enough LOUD BZZZZZZZZZZZZZ!!!!!! when I tried to start it again... don't wanna keep trying it cause I don't wanna fry another solenoid.
If it's been sitting with a dead battery, I would be confident that your battery is the problem.
Why not get out a set of good jumper cables (must be the good thick kind, not cheap walmart stuff)? If it cranks with the jumper cables, it definately means you've got a bad battery.