Wrong Front Brake Caliper ???

My '82 KZ650 CSR was missing the front brake caliper when I bought the bike. Had sludge in the master cylinder and line. I cleaned and honed the master back to life. Then bought a caliper on Ebay for an '83 KZ550, figuring it would be the same. It bolted on and functions well, however the pads only cover the outer two sets of holes on the brake disc, instead of all three sets.
Stopping power is fair, but not great. My questions are: (1) Duh - Would it make a noticable difference to have the proper caliper with pads that contact the entire disc? (2) Does anybody have an '81 through '83 650 CSR who could send a photo of the correct caliper? Or can anyone give a range of models and years of calipers that will interchange?
I am including a photo of what I have now. Thanks for the help.

Bill this is kind of a stumper but I know exactly what you are talking about. I have an 81 650 CSR and when I got it I swapped the mags from a 550 LTD onto it. The front master cylinder was all goobered up so rather than mess with with cleaning it up I just robbed the entire front brake system off the 550 LTD. It fits and works but the front brake does not seem to be real strong and the pads don't appear to be grabbing enough of the disc. Now for the strange part I just looked up the part# for the caliper 43041-1113 and according to Kawasaki the same caliper was used on all the 550's both the A and C models from 80 to 83 as well as the 650 CSR's. I then thought maybe they used a different brake pad but that checks out as being the same. I've just gotten used to the bike the way it is. I thought about maybe this winter changing back to the caliper that came off of it but I'm now not sure it will make any difference. Your question has me sitting here scratching my head. :S

Gringo:
The brake pads for my present ( KZ550 ) caliper are rectangular in shape. These do not cover the inner most holes in the brake disc.

I am attaching a photo of what I think the correct caliper should look like. The pads for this caliper are more rounded in shape, and larger in diameter, than the rectangular pads are wide. Hence, they would cover the greater surface area of the disc and hopefully give more stopping power.

When I go to Z1Enterprises and look at brake pads for my '82 KZ650 CSR H2, is see the rounded pads shown. My dilemma, is in specifying what years and models of bikes that were equipped with this caliper. I do not want to buy the wrong thing again, but must purchase through Ebay, etc., due to economics.

My present KZ550 caliper works flawlessly in case anyone might want to swap parts.