Goody, I have a couple tons of bar stock and heavy flat stock at home. It wouldn't be hard to put together a rig like your model. That was what I had in mind.
Load testing for the engine weight could be done using an inverted stand. Simple hydraulics could apply the load measured using my proving ring. I have the general Dynamics calibration sheet on the ring that defines loads to 5500 lbs in 50 lb increments. The proper rig would allow testing deflection in heavy cornering due to engine weight as well.

My other gauges and instruments could measure deflection down to .0001" in multiple places.

In my opinion, some tests should demonstrate the strength of the K frame separate from the chassis. Any deflection would show additional load placed on the chassis.
The K should stand on it's own as much as possible and not rely on a relatively flexible chassis for support.

Thoughts?

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon