3-speed to 4-speed OD

A good buddy of mine has a nice '66 Valiant V-100 he is setting up as a cool daily driver/cruiser. Car has a 3-speed on the tree, has a short-shaft (from behind a V-8) 4-speed OD to replace. Having never done this swap, can we re-use the 3-speed bell housing? Also, he wants to find a '63-'66 floor hump and needs to get the tabs/arms and shift rods for this- any ideas where to look?

Am also putting an ad in the 'Parts Wanted' section, too. Any help is appreciated!