Seems like similar by block design, but they have sleeve and mine doesn't. The whole idea was to get rid of sleeve-too many problem from it.
This is look like prototypes we used to make in 80's. It was easier to make machined case, to check porting work, but since casting technology went forward, now it doesn't make sence to go for machined case. Still some kids back in Russia do this way, but only on the beggining.