Kz650 front brake upgrade

I’ve got a  1977 kz650 with spoke wheels, and a single front disc brake. Before I change the wheel bearing and tire. I’m thinking of upgrading to a dual front setup. After some research, though the site, its evident i will need a larger brake master cylinder assembly( 16mm) along with lines and splitter, calipers, discs, wheel, axle, spacers, forks,subs even triples, depending.....My question is regarding which KZ model and year bikes can be the Donor for the swap. I’d like to keep the spokes and same geometry, or a  touch shorter fork length would be ok

Thanks for the space and input

Here is what I know. Mine is 78 650B with spokes, so also single disk. However, they moved caliper I think in 78.

Anyways, in my case I will be keeping my wheel, but need:
New master, new calipers, new disks and new forks(tubes). I have donor 79 650C for most of it. Forks look pretty much identical, if someone didn't point at it - I wouldn't notice. Caliper mounts off-set like 1/2 inch to accomodate different disk sizes. Wheel (spoked wheel) has decorative cover but clearly going to take second disk.

Two options using OEM parts from the '77-'80 bikes.

Option 1: Dual disk from KZ1000
parts required:
Dual disks (4.5 min thick) From KZ1000 - these are larger diameter than kz650 C/D
5/8 (16mm) master cylinder from KZ650 or KZ1000  - most 16mm MC will work but be aware of pivot offset as this changes "feel"
dual disk calipers from KZ650 or KZ1000
brake hoses /splitter from KZ650 or KZ1000

Option 2: Dual disk from KZ650 C/D
parts required:
Dual disks (4.5 min thick) from KZ650 C or D
Forks from KZ650 C or D
5/8 (16mm) master cylinder KZ650 or KZ1000 - most 16mm MC will work but be aware of pivot offset as this changes "feel"
dual disk calipers from KZ650 or KZ1000
brake hoses /splitter KZ650 or KZ1000

not recommended to use  two 7mm thick single disks as they will add rotational mass
not recommended to use 1 LH single caliper and 1 RH dual caliper as they have different piston bores and the ratio between calipers and master cylinder may not be ideal for the 16mm master cylinder.

High quality brake pads will go a long way to improving braking as well
 

After some more searching. I’ve noticed it’s much easier to find kz1000 front end parts than 650 w/dual discs. 

Does anyone know of the police package front end will work?
they seem to be available in abundance.
I’d assume that the fork springs would be stiffer for the weight of the bigger bike. But will the triples fit my setup or will I have to Frankenstein the steering stem bearings 


thanks for the input everyone 

I should have specified before but the parts are only inter-changable between '77-'80. Most police bike stuff you will find is from '81+ which is completely different and is not a direct swap.

If I grab kz1000 calipers and discs from. 79-81, will they bolt right up to my kz650 forks and front hub or do I need to change my outer fork tubes and wheel as well.

thanks for all the input guys
AndrewR 

they should bolt right up with 77-80 kz1000 disks and calipers

You could check parts numbers on Partzilla but I think the front wheel is identical to a KZ1000.

Front wheel is the same part. But the outer tubes and calipers part#s differ a bit. Even though the parts look identical