If you're going to use concrete blocks, orient them vertically and set at least two side-by-side on each tier, so they make square pillars. This is good for a stack 24" tall, three tiers. Taller stacks should be even wider at the base. I prefer to use wooden cribbing to set a vehicle up high. I've set all sorts of equipment and vehicles safely on cribbing. My 66 Cadillac sat on cribbing 3' high when I removed the transmission. This was back before cheap two post lifts, when the only other option was a hydraulic lift built into the garage floor, or a pit. I had neither, so I improvised.