There are a number of side stand tabs available through the after market chopper/custom scene as well as other makes (ie: Triumph) that could probably be modified to work for your application if you aren't going for a 100% restoration. Here are a couple of links to a few examples. I've also seen some on Ebay.
The Factory Metal Works
http://www.thefactorymetalworks.com/product_p/fmw-kicktab.htm
Lowbrow Customs
http://www.lowbrowcustoms.com/p1514/buy/m-c-parts/forks-amp-chassis/british/chassic-components/lowbrow-customs-weld-on-kick-stand-lug-mount-for-triumph-or-universal/
Brit Cycle
http://www.britcycle.com/products/830035.htm
Do not buy that Factory Metal Works, Lowbrow Customs, or Brit Cycle kickstand (SAME PART) tab/mount.
It has the spring pin on the wrong side and the thickness of the plate of the tab and kickstand has to match.
Good luck trying to find all that, and then there is the spring problem.
You need to buy a kick stand that has the mount tab and lever with spring otherwise you will have fitment problems.
That mount tab was a Triumph or BSA part left over and they were originally attached to a much thicker frame than the CB750 is.
Buy a kickstand SET that has all 3 parts or you will find out the hard way.
Also the CB750 frame is only 1/16 thickness and all of that welding degradation and stress will be focused on that very short section of the frame.
The kickstand on the CB750 needs a doubler plate (section of tubing) at least 3 times the length of the kickstand tab.
The doubler plate should not be welded the full length. It should just have skip welds on each side, but DO NOT weld transverse across the ends of the doubler plate.
Don't be a wrench monkey -be smart.
I was plannin on welding on a sleeve for strength anyway.
Why would it matter what side the spring is on if I get a kickstand to match?
You could have the spring on top that is true.
Getting a kick stand that has the correct thickness slot is not easy because most
vendors do not list that information.
Many kickstands sold are sold as a set with kickstand ,weld on mount, and the spring.
So if you cannot find the correct length of kick stand with the matching fit, and a correct length of spring you will have spent the money on the Triumph kickstand weld on tab needlessly.
Then you think ... I will just grind down the thickness of the parts or cut the kickstand clevis groove to fit the Triumph kick stand weld on tab. Or I will remove the kick stand spring mount pin and move it to where I want it. Well the tab is so thick and the pin is so small that a 110V wire feed is not up to the job. It would really need to be TIG welded. Oh, you have a 220V wire feed welder. The weld on that little pin will be difficult if you apply enough heat to penetrate the thick metal tab, without obliterating that little pin.
That is not as easy as you think.
I have already gone through all of this when I bought one of the Triumph kick stand tabs. Big mistake.
Factory Metal Works (A good Company) sells the weld on Triumph kickstand tab for $27.95.... Low Brow Customs $34.95....
But you can buy a 1 inch bolt on Triumph kickstand complete with kickstand ,spring, and CLAMP on mount for $39.95 on Ebay
http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR0.TRC0&_nkw=Weld-On+Triumph+Kick+Stand+Tab&_sacat=0&_from=R40You will need to slide the kickstand onto the tube before welding the tube into the damaged frame Since it just has a one piece clamp.
OR you could use a doubler plate and buy the 1-1/8 clamp on Triumph kickstand kit but you must slide on the kickstand mount BEFORE welding the tube of the frame.
Same price $39.95
I do not know what the length of the Triumph kickstand is.