Get the offset bushings for the stock ones and use them. It works just as well and is a ton cheaper and you don't have to worry about the welds. They don't make any difference!!! Use the stock and get a good alignment. I have CAP and they're OK but I was expecting more. I have my stock ones sitting ready to replace them.
Just because you didn't
notice a difference doesn't mean that they don't make a difference. The stock uppers will flex. Maybe not enough under normal driving conditions for the average person to notice, but they can, and do flex under under more aggressive driving.
As far as the welds, I wouldn't worry at all about the welds on the vast majority of tubular arms. With Hotchkis, Magnumforce and RMS it wouldn't even cross my mind to worry about the welds or the construction of the arms. The CAP arms have been documented to have had problems in the past, and suffered from bad welding. But they're also the only outfit that MIG welds their control arms. I ran a set of CAP UCA's on my Challenger for close to 30k miles and had no problems with them at all, but there are cases of failure out there for the CAP arms.
Now, what are your plans for the car? If you're just planning a street driver, than Robbie's suggestion is right on, the stock uppers will work fine, and an offset bushing set up will help you set up the right alignment.
If you're planning a disk brake swap and need new control arms anyway, then upgrading to tubular control arms might not be a bad way to go. The newly reproduced stock arms cost as much as a good set of tubulars, and even used ones command a decent price.
I currently run Hotchkis upper control arms on my Challenger. They're absolutely beautiful pieces. Very well engineered, very well constructed. And for the e-body they're the only UCA's that relocate a suspension point to take out the dreaded anti-dive. But on A-bodies this isn't needed, so they're more like the arms offered by the other outfits. RMS and Magnumforce both offer options that still use bushings (instead of heim joints). This would be a plus for a street car, the bushings make things a little easier to deal with as far as wear and ride quality.
I will say, having set up my car twice now, that magnumforce's "double adjustable" uca's would be really nice to have. Both times I've set up my car with the adjustable control arms I've had to make a few trips back and forth to the alignment shop to get the arms adjusted correctly. They still adjust with the camber bolts, but you have to get the arms set up properly first, and unless you've got all the suspension alignment equipment at home it takes a little trial and error, which with everything but the double adjustable arms requires pulling the UCA at least partially off the car.