AFAIK the only automatic that will bolt up to the 235 is a 2 speed power glide. I doubt you'd be very happy with this 1950s technology. It will over-rev in first gear and bog when it hits second.
I'd start looking for an adapter for a 350 or 700R4 that fits the 235 six. You'll likely have to build your own crossmember as this isn't a conversion that's often done. I'd imagine a shorter driveshaft is required but that would be pretty easy - you just have to measure and give them your cc
A Lokar shifter that looks like a stock floor mounted shift lever but for an automatic would probably work for a gear selector.
For safety, you'll need to wire in a neutral safety switch to prevent the engine from starting in gear and pushing your truck through the garage wall - ask me how I know. The Lokar shifter should come with this switch, but you'll have to wire it up.
You'll need to modify your throttle linkage to incorporate a kick-down cable, especially with a six cylinder
Finally, if you intend to use the stock speedometer, you'll need to get a new custom cable that fits the auto trans. You'll probably have to change the speedometer drive gear in the trans to get the speedometer reading correctly
