Wanted:A833 OD Bell Housing for 340

As I understand it, you might be better off to get the trans first.

:There were three different sizes on production four speeds. There was the 5.125" dia. IBR used on the 1975 and later Overdrive units, the 4.80" dia IBR used on "Hemi" transmissions, and a 4.35" dia. IBR used on everything else.:
--from
http://www.slantsix.org/articles/4-speeds/ODA833fourspeed1.htm

IBR = Input bearing retainer (the groove on the face of the transmission that the bellhousing sits against.)

I have read of people having the inner bearing retainer opening on the bellhousing opened up to the larger 5.125 side to match the OD transmission, and I have also heard of them using the larger 5.125 bellhousing, and a smaller 4.8 or 4.35 transmission, and making a ring that takes up the space between the smaller IBR and the larger 5.125 bellhousing.