bell housing swap

Within a year I will hopefully be overhauling the A833 4 speed in my dart and I want to switch from a 9.5in clutch that was originally behind the 273 small block to a 10.5in. Obviously a bell housing swap will be needed. I am assuming all small blocks have the same bell housing bolt pattern and all A833 transmissions also have the same bolt patterns? I guess my big question is will the bell housing needed for a 10.5 in clutch fit in the transmission tunnel on the car? With the current bell housing clearance is tight, fine as frogs hair. Anybody dealt with this before?