Im shooting a MBG accent 3 pin on the 4" dovetail slider. It has the smaller housing. When I moved from the 5 pin fixed copper john head to this I did not have to move the peep.
I use the bottom pin (my 40 pin of the 3 pin 20/30/40 set up as the slider. I have the 30 yard pin darn near smack in the middle of the housing. I can get about 90-92 yards out of the pin slider before I run into fletch contact (axis 340 and blazers). This is with a 429.5grain arrow. I ran the adjustment almost all the way up to the top then set the gang adjust height to where the 30 pin was pretty much on bit within 3-4" high, then then moved the pin down itself to fine tune. then I set the 20 and 40. 40 is my "trick pin" and slider. Reason I set the 30 pin is because I wanted it in the center of the housing and that is my (dead even) most stable shot. Found this out kinda by accident when I was blind drawing eyes closed. Come to find out, the 30 pin on that 5 pin set up was usually near the bullseye on a 20/30 yard target. So naturally it FELT the most stable had the best float and all.
I shoot 27.5" draw with a 2014 carbon spyder turbo 63-65#.
Note too that your total arrow weight will play a BIG factor in the slider depth that you can shoot at. An arrow at 460+ grains you might not get to 85 with one unless you shoot a high peep/low anchor, which is for the most part unstable as far as anchor goes.
I shoot a 515 grain arrow and get 100 yards out of my CBE with no contact. My peep is in the same place it has always been.
You shouldn't need to mover your peep just because you switched to a slider. You anchor is going to change a little when you start getting out 80 yards and up but shouldn't be enough to make a huge difference in your groups.