The 307 mounts do mount the engine higher. The 69 302 and 350 mounts are the same height as the BBC, but mount the engine back a bit.
http://www.hrpworld.com/index.cfm?tp...action=product
This is the base I used
http://www.hrpworld.com/index.cfm?tp...action=product
This is the adaptor with o ring seal