Thanks for all your help! Much appreciated!Mulleting it will make it considerably slacker and lower, so you want to steepen the HT to correct it. I suggested a +1.5 degree angleset because whenever I plug those into the calculator the resultant change ends up being a bit less than expected.
The offset bushings seem to stay put if you have them on the end of the shock that's not experiencing rotation from the rear triangle movement. So the front mount in horizontal configuration and bottom mount in vertical. I've been running a reversed one on the front eyelet of my Megatrail for several months now and it hasn't moved.
I'm not certain but I want to say that the offset bushings change the BB height more than anglesets do, for a given amount of HT change. So maybe the best for getting back to stock would be like +1 degree angleset and 1 reversed offset bushing.