Can I weld my cam bolts?

Ok, I've set the alignment on my 69 Dart about 7 times, plus 2 times at 2 different shops. I thought it was the shop's fault the alignment was wrong. So I bought a Longacre alignment kit. Set the alignment, drive car around block, and settings are completely different. Tried new cam bolts, then went back to the original bolts. Tightened them with a breaker bar. Still alignment changes when driving. I thought I read that A bodies are troublesome, and tack welds are needed. Is this a good idea?