I think the 350 trans was retired before the 86 model year, so if it’s in fact a 350 someone swapped it.
If the 2 pin connector looks like a oil pressure switch, it’s for the transmission controlled spark. Pretty sure you won’t be using that with your crate engine. Pull it out, thread in a 1/8 pipe plug, problem solved.
As for the converter switch, there are a couple ways to go about getting it to lock. Pull the pan, find the pressure switch for 3rd gear. You need to know if it’s shows a ground when it’s pressurized. Or, if your lazy and just want to buy the correct switch go to your nearest transmission shop and ask for a normally open pressure switch. In other words, the switch connects to ground once the trans goes into 3rd gear.
You will also need a 2 wire lockup solenoid. One wire of the solenoid will go to the pressure switch, the other wire to a activation switch. Since you have a 86 truck, with the headlight dimmer on the column, the cleanest switch would be to use a headlight dimmer switch. Use that to supply power to the solenoid. Turn on the switch, once the trans shifts into 3rd gear the converter will lock.
They are also aftermarket lockup controllers that include delay timers to delay lockup activation (gets rid of the 3rd gear/immediate lockup) vacuum switches (automatically unlocks the converter under heavy throttle) brake switches (gets rid of the jerky sensation when you get on the brakes and back on the throttle) it just depends on how fancy you want, and how much you want to spend.
All of this ASSUMES you have a 350. If it’s a 700, most of what I said applies, but you need to make absolutely sure the TV cable is installed and adjusted correctly if not, you will burn up the trans almost instantly. A TV cable is not the same as a 350 kickdown cable!!!
