If I were making any changes to Scott's plans, I would have the lifting arms run along a traveler that let you hook the stand up to the car starting from rest on the suspension. It was inconvenient to lift the car way up to get things hooked up. In other words, the vertical arms would be 48" tall and a concentric sleeve would slide that entire length. As designed, these telescope and that limits minimum height for hooking things up.

The hydraulic rams are not that important when you can use a single engine hoist a several inches at a time alternating each end. You raise it to position once and leave it, so rams are a conveniance, not a necessity.

The base should be very wide. Casters should have their center of gravity reduced just like you see in Jim's stand and on my alerations to Scotts stands. Front and rear stands should be hooked together. I know folks have gotten by with two cheapie engine stands but I don't think it's wise.

Jim, you're stand it getting dusty. Time to start a new project. Or eBay it? Looks like a genuine Ram Air rotisserie to me.