I do not want to be disrespectful but I cannot understand why anyone would want to go backwards with technology and choose a carburetor over electronic throttle body injection. TBI gives more reliable starts, no missing, spitting, coughing when cold, better driveability.
The 1987 3.9 had a carb. I had one and though there was no change in ratings to the TBI engine, the 1988 I bought to replace the 1987 felt much stronger.
Besides the carb, you will also have to address the ignition as the TBI surely provides feedback to the ignition. And the electronic ignition conversion kit for the 3.9 is long gone.
Aaaaaa, the distributor debate. 1987 is a one year distributor with our favorite hall effect electronic ignition system, so it can be altered to survive a carb change a little better than our hated Lean Burn system.