I've never had one in my hands to verify that the dimensions are correct. If the dimensions are all correct then I can see how it would be useful but you have to store it and it isn't useful for much else. For those reasons I just keep a spare block or two in my shop. That way I'm working with a real block that has the correct dimensions. I do have a dummy transmission that I use so I don't have to lift the real thing in and out of the car.

The local chassis shop is building a gasser B body right now and they borrowed a bare block, bare trans case and a set of bare heads from me so they could build engine mounts and fabricate the headers. That way the car will be ready to go when the customer gets his engine back from the engine builder. The chassis shop has Chevy engine cores for mockups but they didn't have a Mopar core so they asked for help.