The bolts attaching both back and front discs are 10mm x 32mm x metric fine 1.25mm pitch thread. Whilst the items on the bike are seriously scabby they are functional. I am trying to replace the vast majority of the fasteners on the bike to A2 stainless, but metric fine bolts appear to be as rare as rocking horse shit, and when one finds them they seem to command a king's ransom.
A local fastener supplier has offered me some cap screws. Obviously using the these would make the tab washers redundant. The discs on my old EXUP thou were held on with six 8mm buttton head screws locked with thread lock if memory serves mr right yes I had to replace a disc -
the old lets ride off enthusistically with the disc lock on!
Is there any reason why it wouldn't be appropriate to used the same method on the Big Zed? I'm not too fussed about the originality angle, but will keep all such parts in case I am one day

Ralph Ferrand
Z1000A1 (1977), Z1300A5 (1983), Z900A4 (1976) GPZ1100 Unitrak (1983)(project), RD250B (1975)(project), ZRX1200R (2005) DT175MX (1981) YZF R6 (1999)
http://www.bikerstoolbox.co.uk