The Cleveland is basically a Mid-Block and partial to the Modified Engine Family (351/400M engines) The trans is the same as all the small blocks and the engine mount bosses are the same too. However, i believe there are specific motor mounts for puting the 351C into the stang that lower it down just a touch. So the mounts you have from the 302 will probably work, but won't necessairly position the engine correctly. Give it a try, what the heck?

obviously the exhaust won't be the same either but there are headers available or go with early casting 351C manifolds for the best clearance.