rear brake help, 2000 kat 750

[fflier9]

Hey y'all. I'm rebuilding the rear caliper on my bike because it was filthy and the pistons no longer retract. I have the pistons and bores clean and am ready to install new seals but I'm unsure of the orientation. The old ones were too corroded to tell which way they were facing when I pulled them out.
The service manual doesn't say anything about the seals rear caliper, although it has this diagram for the FRONT BRAKES, (not the rear) but I wanted to be sure...everything online says to face the tapered part of the seal towards the piston, not the wall of the cylinder, like in the diagram, so I'm just confused....
Thanks for your help

[fflier9]

Also if anyone knows what to do with the diaphragm in the rear brake cylinder if it has expanded greatly, like am I supposed to compress it all back together?
It unfolded like an upside-down pyramid and pushed a lot of brake fluid out of the cylinder when I tried to put the cap back on.