I've used the small wooden dollies a bunch of times. Flip them over and look for flaws in the wood before you buy them, it also seems like they use whatever wood is on hand and some have a harder species or different grades. Between a friend and myself I think we had one fail out of a dozen. For a big block car you could always take some scrap wood and double up the frame, the casters seem more than adequate. Just don't abuse them and they will do the job. They work better than trying to drag the car with just a jack but you'll still have to rock them a bit to get them moving.