I haven't had much luck with a shrink disk but it might work for that job. We use a stud welder with a shrink tip to shrink metal but it's a lot more expensive than a disk.
i don't have a stud welder, so i use my tig torch instead. same principle though, heat and cool a small area. it's amazing how effective it is. i do small groupings of spots, trying to be careful not to do too much at a time.
From what you said and what I am envisioning I would say no. Shrinking discs are typically used in an area with very little raised defects about the size of a quarter or half dollar. They are meant for fine tuning the panel when a torch or shrinking tip might be an overkill. I have been using those discs for about a decade (both the 4" and 5") and find them extremely helpful when fabricating new panels, but they are only meant for fine tuning very small areas. In my estimation you have several choices to choose from, hand torch, shrinking tip on a stud gun or a shrinking tip used on your mig welder. The shrinking tip for mig welders may be a very viable option to you, but make sure you practice with it before you apply it to panel. I use all three of these methods during panel fabrication. The fact you own an english wheel, I can say you need to become versed in each of these methods. I have been using an english wheel for 40+ years and can say they are one of the hardest tools to learn when starting out.