Wheel swap 76 kz750 to 77 kz650

Hello All,
Have a couple different questions but will address this one here....I have a 76 kz750 with mag rims, disc in rear and want to put them on my 77 kz650 that has drum brake in rear with spoke rims. Sorry if this seems too simple but I tend to over analyze things. Anyway the 750 has the rear master cylinder and everything to do this switch, so where can I mount the master cylinder on the kz650 ? Keep in mind I do not have a welder, and wouldn't know how to use one if i did have. I forgot to mention that the tire size is same on both bikes.Any help would be greatly appreciated, or any opinions about this swap.
Thanks and I will see you in the engine section shortly

I'm confused. The '76 KZ750 was a twin that came with wire wheels. Are the mags you mention aftermarket? Also, keep in mind the '77 KZ650-B1 (rear drum / wire wheels) uses a different swing arm than the '77 KZ650-C1 (rear disk / cast wheels) or the '76 KZ750. The KZ650-B1 swing arm has a different torque link mount; it's on the bottom for the drum, the torque link mount for disk is on top. The torque link is also different than the one used for drum brakes. I suspect you will need to find a competent welder to make the switch. Ed

I think the rear axle bolt is bigger on the 750 and will not fit the 650 swing arm. The front mat fit but I am not sure.

Ok I should clarify first I guess........The kz750 mags might not be factory?I have a pic of them on one of my first posts I left on here if that helps. It just had them on it along with some after market parts accel coil, drag handlebars, header exhaust etc .. If I ran the V.I.N. could I find out what "should" have came on it factory? That really sucks about not just being able to put em right on.I'm not certain whether mine is B1 or B2,can I tell by V.I.N. or motor number. The owners manual says C-2. Thanks again