1969 Mustang bellhousing issue

My brother is in the middle of rebuilding a 69 mustang, he bought the car with the original straight 6 with the 3 speed manual, and it also came with a 351 Cleveland. He wants to put the 351 in the car instead of the straight 6, but he needs a new bell housing for the transmission. all of the bell housings he can find are for the 351 Windsor not the Cleveland, does anyone know if they will still be compatible. Hes searched for one that is for the 351 Cleveland but everything he finds says Windsor. Any info would be awesome. Thanks