The 13/14 GT500 motors had that process, same with the Coyotes - aluminum block with a spray coating on the bores. Aluminum jug dirtbikes are similar too, some are sleeved but many are coated. There is a ton of work in the design of a modern aluminum block, and the RB block has bigger mains, bores and 1-2" taller deck height than a coyote or LS, so there is more growth for a given temp compared to a smallblock. I don't know of any modern big blocks from the factory with aluminum, the GM 632 crate motor would've been a great opportunity and GM decided to make that one in cast iron.