Seems to be quite a bit of meat left there than what it sounds like @Yarp has to deal with.
Makes little difference really, a few mm protruding to hold the nut in place is ideal, then you can fill the nut with weld
and get plenty of heat into what's left of a bolt/stud/etc
You need to be careful that you don’t damage the seat of the bleed nipple in the caliper, otherwise it’ll never seal.
What caliper is it on? A blue bmw caliper by any chance?
IRS (Independent Rubber Suspension) Axle Repairs
Full Re-rubbering of IRS (Independent Rubber Suspension) axleswww.fraserbrowneng.co.uk
We use this kit in work, have to phone to order it but they do the business. Have also had success with 4 pot calipers using these too.
Buy cheap, buy twice.Those look very similar to the Nielsen ones I posted but about 3x the price.
Buy cheap, buy twice.