I've got ZRX1100 shocks on my '78 KZ650.
The ZRX and the KZ are both close to 500 lbs.
The shocks are longer than stock, so I raised the front end up to stock (had it lowered for years).
Ride is fine, I'd do it again.
The KZ doesn't have a chain guard:

Here's a recent pic of my bike with the KYB shocks on it, and a pic of Eddie Lawson's personal KZ1000R.

You can see the special factory bracket to support the chainguard.  It's an easy part to fabricate.

 

I got rid of the 40 year old pogo-stick shocks, and installed ZRX shocks on my '82 GPZ1100.  Check for shock spring to chain clearance (it's real close).

You can keep most of the chain guard by removing some material, like they did with the ELR chain guard.  There's even a special bracket to stabilize
the chain guard (#11036).

You can see what the chain guard looks like on my GPZ, after it was trimmed.

At some point, I will probably have the shock moved outboard, using a new mount from Z1 Enterprises (part #DC104CL.  $9.95/ea.)

 

I didn't notice any different in height and the rear suspension is a little firmer but I'm OK with that. The ZRX shocks are adjustable. Here is a pic of what I had to do to my chain guard. 
I'd definitely do it again. 

You might want to check clearance at the exhaust if the stock system is being used.

Jim,

With the shocks being a little longer, and coming off of a heavier bike presumably having a stronger spring, how drastically did that affect your ride height?
Did you do anything to compensate for it (i.e. new or modify springs)?

Along those lines, with springs/dampening designed for more weight do they still work well on a 750 sized bike... in other words, would you do it again?

Since it's been answered already.  From the only KYB pair I saw on EB, my eyeballs tell me it's kind of obvious that the coil spring will rub the chain guard, since the spring extends almost all the way to the lower shock mount.  The lower section of KZ shocks below the springs is kind of narrow.

I have them on my GPz750. They are a little longer, interfere with the helmet lock (I removed it) and rubbed on my chain guard which I had to modify. 

I need to replace my worn out KZ750 shocks.  It appears that ZRX takeoff KYBs can be found for $200-$300.  

A search revealed that this has been asked before, but I find conflicting information... "bolts right on"... "too long"... "too wide, interferes with chain".  Just looking to hear from someone who's actually done (or attempted) it.

Thanks!