1982 KZ750E oil cooler installation

Hello,
I have a 1982 Kz750e, I would like to mount an oil cooler, so I think I will bought a 1982 gpz750 oil sump.
I have read somewhere tahat this sump will fit exactly kz engine, in my understanding the only difference whit the original one is the presence of the oil pressure sensor.
After doing this kind of job, I will be able to fit an oil cooler.
But my question are:
1-gpz oil sump is really 100% compatible?
2-my kz, doesn't have oil pressure sensor wiring connections, so I will leave it only for close the hole in the sump; is it OK o I need to wire it?
3-is it possible to fit only the GPZ cooler or are ok also the most recent ZR cooler (bigger than gpz's)?(the lines connection on sump side seem the same but I'm not sure)
4-and the most important, installing the sump and oil cooler on a motorcycle thinked without they, can lead some problems? Like wrong oil pressure or others?
Also the chose of the cooler dimension can lead different problems at the engine if it is too big or too small?
I hope someone has already done a similar job and can help me.
Thank you in advance.

I put a GPz750 cooler on my KZ750. Install a oil pan with the outlet ports and a GPz cooler. Done. Both bikes share the same oil pump and pressure relief valve so you can rest easy. The early KZ bikes use a mechanical tach drive so you are limited to how big the cooler can be or the tach cable will hit the cooler.

The photo below shows the type of oil pan to look for with the oil level sensor blanked off.

I have found the one in the picture, is it OK?
I think yes, but I have seen that there are also different models.
Is it same of the one fit on your bike?

I can't say for sure based on the photo but it looks right.