89 f150 donor, what sensors do I need for MS?

I got a 89 f150 donor, I am pulling all the elctronic harnesses, motor, lines, etc. What do I need to run MS, what can I remove. I assuming smog pump and all of its stuff can be ditched.

I know I will need an O2 sensor, one on the truck wont come out. What else do I need, should I grab?

Take everything including the PCM and the harness, sort out what you need as you go forward.
IIRC you'll find that there is a MS configuration that fits in the standard Ford EECIV enclosure and uses the stock harness.

If you are serious about Megasquirt I would strongly recommend that you check out the Megamanual at:

http://www.megamanual.com/mtabcon.htm

There is a lot of information in there which can be a bit overwhelming, but take your time to get a good grasp of how it works. Only then you will be able to decide whether MS is for you or not. It's really not all that difficult once you understand the principals and the newer versions can do almost anything for anybody.

throttle
coolant
map
air temp


that should be the bare minimum.

you can get a kinda piggyback setup. you use a donor ECU for the case and plug. Jumpers are used so you can match the pinout to your stock harness. a cable will connect the donor ecu case to your MS box.

this will let you swap back to a stock ECU in a few minutes. I think this is a waste since most likely you are modified to the point a stock ECU won't work anyways (different injectors, boost, etc) if it were plugged back in. Not to mention if you are deleting some emissions equipment the stock ecu will not like missing it. There is some added cost in this piggyback setup.

You can use any sensors from any motor though. the newer GM metripack based stuff is super common and cheap and the plugs are very affordable.