I built mine as well.

Here is a rotissorie I built several years ago. I featured it before over on Garage Journal, one of several other forums I frequent.

Features include: (1) arbor locks with spring loaded pins where the pin handle holds the pin in the retracted position for one man operation; (2) hydraulic jacks for raising but hitch pins in double shear to ensure arbors are concentric; (3) bushed center of gravity adjuster to raise or lower body to adjust for balance (use deep well socket and impact gun on coupling nut); (4) caster wheels with brakes at all corners - I used an oil pan drain bolt to lock wheel at 90 degrees; (5) push handles on both ends.

I studied many designs out there before building this. Most suffer from lack of keeping the arbors concentric which basically creates a bent crank and impedes rotation. I wanted to ensure concentric axis of rotation yet be able to tune the offset to get the car's CG on the axis of rotation which then balances the body. The nut and pneumatic impact make it quite easy. The hitch pins keep the axis of rotation in alignment without stress on the jacks