Want to build a body jig

[Jclgodale3]

Getting ready to lift the body from the frame and want to build a mobile jig to set the body on. Have read several posts regarding this but wanted to know if anyone could share specs on how the built theirs prior to sitting the body on it. Caster type and count? Mounting points? How high the body should be once set on the jig for body prep etc. Any help would be greatly appreciated...