School me on the 4 speed, please.

I know pretty much nothing about the 4 speeds and i am looking to convert my 69 swinger to one. The car was a stock 4 speed, but the last owner put a 727 in it. The car has the clutch pedal strapped to the fire wall still, so I am lucky there. But I am assuming I will need some linkage for the conversion. The car has a 340 in it.

So, that being said, which transmission do I need, I am assuming the 833?
Where is the best place to find one or what car to get it one out of? Shoud I watch Craiglist and e-bay for one? Anyone here got one for sale?
How much is a reasonable cost for one?
Is there any other transmissions I should consider as far as an upgrade or anything?

I am new to the car resotoration deal, but so far I learned a ton from this forum and working on the '71 Swinger I started to work on but sold when I got my '69.