Another option would be the engine from any of the MPC early 80's
Ford Bronco kits as they are supposed to be 400ci and that engine
is part of the "335" series that Ford produced which included
the 351C, 351M and 400 the latter two were essntially the same as
the first only basically smog motors and used the big block bellhousing
I know there were other minor differences but it will pass for a Cleveland
easily I may have one floating around let me know offline if you want it
also you can use the valve covers from the MPC/AMT Boss 351 kit!
HTH