My 1968 Mustang will not start.

I daily drive a 1968 Mustang, and have come across a problem. Around 2 weeks ago my car started to act up. When putting the key into the ignition and going to start it, nothing happens. I know my battery isn't acting up because it's new and my car has power. At first I thought it was my starter, but after messing around i attempted to start the car through the starter solenoid. With the help of my dad, I had him turn the car to the start position and I ran a screwdriver from the battery cable to the solenoid.
For a week or so this worked. After trying to start it last week that failed. I thought my ignition went out, so we replaced that. Still, nothing occurred and the car wouldn't start or attempt to turn over. We jumped the car assuming that it was dead. that wasn't an issue. We tried bypassing the starter using the screwdriver trick, you could hear the car trying to start but once you let off it dies. I just bought another solenoid along with a voltage regulator. On the 26th I'll try installing those and attempting to start again. If all else fails, I'll buy a new starter for the car. Any tips? My pops and I are at a standstill and need help! Thanks a bunch everyone!