Hi Mike, some ideas from my build.
I'm keeping the engine monitoring fairly minimum. I will be trying to run an ECU with fuel injection.
On the dash I will have engine rpm, water temp, oil pressure, voltage. Then I will try an O2 sensor separate to the dash, maybe only for initial tuning.
Some tips:
Oil pressure sensor - lots of people put in a sender with npt thread (1/8-27) but thats wrong for the japanese block. VDO do senders with the right thread part number like VDO 360-081 with 1/8-28BSP thread (or R1/8). The whole part might be VDO 360-081-032-057C, but just check the thread is listed right.
Water temp sensor - Since I have an ECU the factory water temp sensor is wired to that. I found another water temp sensor that can fit in the next spot where the original radiator fan switch was installed. The part is a Koso P1/8X28. It took a little time to get my MGL instrument calibration worked out to match what the ECU was seeing, but not too difficult.
Gary