In regards to upgrading your B230F engine to have an oil pressure gauge, here's some additional information that you'll need:

The oil pressure sender is in the same location on the B21FT (turbo) as it is in the B230F engine in your '86. The one on the Turbo vehicle is a 1.5 inch cylindrical can shaped object with two spade plug attachements for the wiring (one is for the idiot light, the other is the variable output to the guage, and the ground for both is supplied through contact with the engine block). The turbocharger is in the way of reaching it, so I would suggest taking 10 minutes and removing the alternator. This will provide the room needed to get a pair of pliers or channel-locks in to unscrew the pressure sender unit from the block. -and be sure to get the little elbow if a seperate brass one is used along with the sender.

Now that you have the pressure sender and the gauge from a 240 Turbo, you'll need a thread adapter that will go from 14 X 1.5mm to 1/8" NPT (because the threads in the block are different). SunPro makes a mini-kit with 5 of the most common thread adapters and this is one of them. The part number is SunPro CP7573 and I recently picked one up at AutoZone for $4.99 plus tax. Just give them the part number and it will come up in their computer. I believe that PepBoys also carries this kit for about the same cost.

Of note, the accessory gauge cluster is not a Plug & Play addition for any car other than the '81-'85 Turbo 240s, so you'll need to run an extra wire for the gauge and re-splice the connector for the idiot light. You'll also need to provide +12 volts and a dimmer-signal for the lights in the gauges. If you grabbed both halves of the 6-pin connector, it will make it easier for you to wire it into your car if you have a working pigtail to splice to (and make it easy to remove for troubleshooting). If you're not thrilled with the idea of moving your radio the lower pocket by the trans shifter (to accommodate the gauge pod in the upper cavity), build yourself a cover over the gauge cluster and mount it on the dash above your radio. This can be done quite well and you can even grab some dash material to cover it an make it look like a stock option. -or consider mounting just the Voltmeter and the Oil Pressure gauges in the two available slots to the immediate right of your instrument panel. If you want to add a vacuum/boost gauge after that, use an aftermarket pod and attach it to the A-post along the left side of the windshield.

Be advised, the 3-bar pressure sender is different from the 5-bar pressure sender. Once you've got the sender off the vehicle, scribe on the side if it goes to a 3-bar or 5-bar gauge.

Congradulations on your exceptional day at the yard! God bless,
Fitz Fitzgerald.
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'87 Blue 240 Wagon, 246k miles.
'88 Black 780, PRV-6, 145k miles.