Hello Clint
Your best approach is to build the 240D generator.
Slowly put it under full load while watching Volt/AMPS/RPM and step up RPM as needed + make notes of what RPM = which load.

Please note:
You will need a signal conditioner to preserve electronics in the house.

:EDIT:
Thank you "leathermang".
Going to fast and assuming too many things.
Allow me to clear up what I was trying to communicate.
#1. Build it to run off the transmission output shaft.
#2. Take lots of notes and pictures, some of us might want to duplicate what you are making.
#3. Rough your RPM into range with no load.
#4. Start applying electrical load.
#5. Mark linkage positions for required load levels.

What you really need is a loader/unloader, similar to a cruise control, this monitors generator RPM and adds engine power or removes engine power to keep a constant speed.

Central A/C power spikes are hard to smooth out on a generator

You should find 500 - 1500 engine RPM variation no load to full load.

__________________
ASE Master Mechanic

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D

https://www.boldegoist.com/