1970 Other Chevrolet Models 70 Chevelle Won't Start, Battery

Here's the deal, my father restored cars and when he died we got 3 of them. We're trying to keep them running anf nice, but we have no idea what we're doing

We've put in a altinator, battery, voltage regulator and plugs. We've already checked the battery terminals and ground.

When I turn the key there's nothing, no clicking.

Acouple of months ago, after jumping the car, it start and run, but would not start again.

Thanks