Can you notch out the flange enough to clear? Or can you unbolt the back of the cat and try bending it again? The rest of the exhaust might be what's holding you up. I'm not sure how your able to get both pipes hot enough to bend at the same time, that could be your hang up as well. Since your in the middle of a SAS job, I'm betting you have the skills and tools to notch out the down pipes to get the bend up you need and weld them back shut, naturally you will have to do the same behind the cat because of the angle it will create, the pipe will have to bend in two spots. Pictures would be a huge help. From what I'm picturing though, the ideal fix would be to cut both down pipes where they are vertical, remove enough to get your clearance, tack them back together then remove the y pipe and weld it back together. I bet that if you use a torch and get the nuts to barely start to glow you can get them off with a 6 point socket way easier than you think, i do it a couple times a day working in a tranny shop, and we get some bad ones sometimes. Then buy brass nuts to replace them with. The brass won't rust and lock on like steel nuts will. Antiseize helps too. Something else to consider is that by moving your exhaust up, you will probably have to make a change to your first set of exhaust hangers because they probably won't be doing their job anymore. Hope this helps, I'll check back a few times to see if you shoot down any of this, or if you put up a picture, If it won't work, say so. Knowing what doesn't work helps to figure out what does.