833OD bellhousing?

Yes, it can be changed to accomodate, but there is only one way to do this. This is because you can't just change the bearing retainer if you want to keep that case with that bell.

The case has a bolt circle with a 4.160" diameter. The bearing retainers that use the 4.160" bolt circle pattern are either 4.807" or 5.125". You cannot put a 4.354" bearing retainer on the case that has a 4.160" bolt pattern, because they do not match and even if you opened up the holes, the heads of the bolts themselves would interfere with the 4.354" bellhousing circle.

the difference between 4.354" and 4.160" is only .194", which is just shy of 3/16", which is not enough room for the bolt heads and may not even be enough for the threads to clear 4.354". You simply have to use the 4.160" pattern on the case with one of the larger bearing retainers that have the wider flanges.

The clutch fork pivot bolt holes, next to the 4.354" diameter index hole on the bellhousing is too close to open the bell up to 5.125" and the bolt circle on the trans case is too large to use a 4.354" bearing retainer.

This means that you have to meet in the middle on both the bearing retainer and bellhousing, at the 4.807" diameter, but you don't cut all the way through the bellhousing at that diameter. You only go as deep as you need, to get the flange of the bearing retainer into the bell. It only goes halfway in, anyway, so the idea is to leave as much material in the bell as possible, so the bolt holes that hold the fork pivot in place have enough material between them and the index hole. The bolts come in from the front of the bellhousing on the fork pivot and only go partially in, anyway. So you have the bearing retainer going partially into the bell from the back, and the bolts for the fork pivot going partially into the bell from the front.

if you have a case with a 4.160" bolt circle that has either 5.125" or 4.807" bearing retainer and a 4.354" bellhousing, you have enough parts to complete the transmission, you just have to machine partially into the bell and make sure that the bearing retainer is at 4.807", either by leaving that one in, if that's what you've got, or machining the 5.125" retainer down.