There are other blocks that can be adapted, e.g. Fontana (and Arrow, and DART). They may be hard to source.
From someone who is running a Fontana....
"The Fontana block is actually a cross between the Cleveland block and the Windsor block. It uses a Cleveland crank shaft and oil pan, but has a Windsor style front timing cover and the intake manifold is a Windsor type. They were made in both 9.2 and 9.?? deck heights. The other blocks I believe may be of the same design."
Hope this gives you some other options to consider....
Rocky