Sorry guys, my 1980 emissions controlled monstrosity had lambda feedback. It was simply a matter of pulling the stock O2 sensor and replacing it with the wideband sensor.
My sensor is located near the transmission tunnel below the shifter.
Mercedes engines and more Benz accessory from Performance Products
I drilled a hole in the lower part of the transmission tunnel right in front of the seat cross member. I put a gromet in and sealed with silicone. I ran the wire to the stock ECU location in the drivers compartment. I like this location because the LC1 electronics are inside the cabin. I would have prefered to have it under the hood though and wired directly to the relay board instead of having to splice into the harness.
I caped the EGR hole in the exhaust manifold with a brass cap. I don't know if there is enough exhaust flow here for the O2 sensor to function properly???? I would also worry about only getting a reading from one cylinder (probabally ok but beyond my knowledge level)? Wiring wise it would be a perfect location.
I hadn't thought of this but it would definitely be a lot easier to have an exhaust shop weld in a bung while your car is still driveable. (Welcome to the discussion bluefang!)
P.S. If you come across any other issues that I have neglected to address please let me know and I will post them on my site. (I just added a preinstall checklist including O2 sensor bung installation) Thanks, Mike.