Suggestions on performance upgrades for 225

Im the new guy here. I just got a '61 Dodge Lancer 775, and have been experiencing starting problems. It had a bad negative ground btty cable, I changed it plus new external volt reg. Came with new alternator. it won't crank the starter unless I use my carved up portable lithium starter on btty. It runs fine unless I use electrical lites, etc. Dies and won't start w/o boost from portable starter. I took it to O'Reillys, no agreement on next step. Thanks for any help.