[D13]

The biggest problem with the 700 swap will be the TV cable. GM never put it behind an L6 in the US (might have in Argentina). The TV cable is critical for 700 (controls line pressure like the old vacuum modulator on a TH350) and the geometry of the cable to the carb is critical for good driving and trans life.
Assuming its a 3 speed manual, you will need an auto column or a floor shift. Since it's an 83 you probably have a cable acellerator and a staged 2bbl carb and you can rig a way to drive the TV cable (look at TCI and Lokar for some ideas). I have not done this personally but I understand that the cable connection at the carb can be difficult to make and route. The calbe itself will probably have to be longer (custom) since your carb is further away from the trans. You will have to measure the trans and your existing shaft and eiter cut it or put in a shaft from an OD equipped truck, and possibly the trans support too. If you can find a junk yard donor 83-86 with the OD trans set up (very common) and get the xmember and shaft you'd be way ahead.