The fact that you are getting a spark with no battery fitted means you have a CDI ignition. No battery required.

The presence of spark also indicates that whatever the state of the rest of the wiring, the ignition is on.

Keep kicking and using a puff of ether starting spray every now and then.
You ...

As NASA are famous for saying.....
'Given sufficient time and money, we can do anything!'

'e' engine will not easily fit into the 1VJ, but it will be more easy to put in 3AJ.

The operation was a success, but unfortunately the patient died!

It gets sprayed from the pressure oil feed that lubricates the big end.

22.01 mm or about 0.0004" clearance.
Just enough for a film of oil.

Try giving the crank ends a rap or two with a copper hammer. As you tightened the right side nut it would pull the crank to the right, if the left side bearing is tight in the casing then you will get some preload on the bearings which could be the cause of the problem.

If that doesn't work back ...

Module just arrived two days ago. Looks the real deal. Wont get to try it for a couple of weeks, but I will let you know how it goes.

If you need an ignition module for your XTZ750 or maybe a spare if you are travelling and don't want to pay $300+, this unit from China for $18 may be the answer.

https://img.newfrog.com/products/2/4/4/244518/244518-1.jpg

https://www.newfrog.com/product/universal-cdi-box-unit-for-yamaha-virago ...

If you can count to 5, you probably don't need one!

As an experiment to try to find the problem, do not turn the ignition on until after you have positioned the piston at just after TDC (ideal kicking position).
Turn ign on and then kick.
Let us know what happens.