To go from carbed to TBI is pain full. but it can be done
1st off the trans is not a 700R4 if its TBI most likely a 4L60E
I am not sure how to tell them apart but the 700R4 does not need a puter the 4L60E does.
Ok even though you are in small block land there are some differences.
You will need to know this stuff:
If the items are stock
The 84 will have the old style valve covers 4 bolts on the side
The 87 will have the 4 bolts on top this is the 1st generation of the vortex's.
The diff between the 84 & 87 also is the intake bolts the 84 is old style & go in on a angle thru the intake into the heads.
The TBI {Throttle Body Injection} intake bolts go in straight {90*} into the heads*.
*side note; some people will ream out the holes on a carbed intake to fit the Vortec.
To use the TBI you will need to install the ECM{Electronic Control Module} & the wiring harness that goes with it map sensors O2 sensors & all that jazz.
Now there are all kinds if aftermarket variations for both of these .
And most important I do not know them .
Well this it the Information that has freely flowed out of my old decrepit brain box @ the moment.
Hopefully some people with more knowledge will chime in & fill in the blanks I left open.
Rob