I can weld just about as well as any professional. I wouldn't have known there would be rubber in the perches. AND I'm familiar with these trucks. Just goes to show I learn something everyday.
I agree with the idea to cut off the old perches and reweld on new perches. If there is rubber dripping out of the weld, that is a contaminated weld.
Where the weldor went wrong was that he should have said, this is a part I'm not familiar with, I started welding it and rubber is dripping out. He should have gone on to say this is a Band-Aid patch job and the right thing to do is either burn all the rubber out (you do it because I don't want to breath it - and burn it out with a propane torch yourself) but ideally, order new perches and when you have them, I'll come back, torch off the old perches, grind the axle tubes and weld them on after you set the pinion angle. HE SHOULD have said DO NOT DRIVE this vehicle, these welds won't hold. There was nothing wrong with him taking payment. Time is $$$. You're paying for his time regardless; he kind of got a bad job.
Or just put a Nova rear end in. I put one in a 52 3100 20 years ago. It went in about 20 minutes. I used the stock perches and brackets from the Nova and the 52 3100 springs. It wasn't correct, but I drove that way for years.