Brake rebuilding quesions on KZ1000st

I'm at the point in my project that it's time to do the brakes. Does anybody know where I can get the rear master cylinder dust boot from? Is it the same as the newer police bikes?
The front calipers have thru bolts with rubber shanks that the caliper mount rides on. The rubber is destroyed on 2 of the bolts, Do rebuild kits come with new rubber sleaves? ( I'm not talking about the boots on either side of the mount, It looks like a regular bolt but the center portion of the shank is covered in rubber)
Can I buy the sleaves seperate? or am I screwed?

Those are just dust covers on the inside of calipers to keep crud from between the sliders and inside caliper body,Z1e should have those I change the dust seal outside of piston at same time

Heres what Z1 enterprises lists for caliper rebuild kits for 79 kz1000e.
Looks like $35.10 for each kit,you might try calling them about seperate parts though.

Thank you for the help. I ordered the kits from Z1, recoated the cutout on the bolts with some super strength black silicone and found a dust boot from a XS650 that should fit.