How to choose offset front sprocket

Aloha guys.

Just as the title reads, just how the heck do you choose the right offset?

I do have Zep400 swingarm and probably gonna fit Zep400 rim to it. Now, the motor is from 82 KZ/GPz 750 so I know I need to fit offset front sprocket. Just how do you measure the offset? I do have the laser pointer along with chain alignment tool.If I have to, I will go to those Japanese motorcycle guys (I do read and write Japanese)but I just don't know how to measure it.

Can anyone shine me a light on this?

Get your back end set up as you want it, fit the back sprocket and the original front sprocket. Laser down one face of the rear sprocket and measure the difference twixt the laser line and the same face of the front sprocket. That'll give you how much you want to offset your front sprocket. If its close enough to a standard offset,you might be able to adjust the back end to get it on the nose. If its way off, you might need to get one made up special.
I was lucky enough to be able to use an off the shelf one.

It's quite easy, center the swingarm in the frame then center the wheel using the frame centerline. Kawasaki centered the rear wheel on the frame centerline not the swingarm. You will notice on a lot of bikes the rear wheel is not centered in the swingarm. So as long as the rear wheel is centered within the frame the front oem sprocket will automatically be in line with the rear sprocket. I've swapped a lot of awingarms on a lot of bikes and this has worked most of the time. Now sometimes it doesn't due to some weird combo that is when I end up using offset sprockets

Got it.

Thanks guys. I will definitely use laser pointer to get accurate measurement.