1982 cb750 Nighthawk Gas Tank

The gas tank on my '82 cb750 Nighthawk is leaking. I think the leak is coming from the fuel gauge sender unit gasket under the tank. I replace the o-ring gasket but, of course, when tightening the nuts back up, I snapped one of the posts off the tank.
The gasket does appear to have helped but of course it still leaks, albeit a little slower now.
I've looked into having a cut off bolt welded to the tank and still consider that an option. However, there is some minor body repair to be done AND it appears to have been lined in the past before as you can see cracked lining inside the tank from the fuel cap opening. So now I'm wondering if it's even worth the time of trying to get my current tank repaired if I'm just going to run into problems down the road from the previous lining chipping off.
The problem is - that is almost impossible to find one of these tanks either from an SC model or from another model that will fit it (I've read that a c or k model from the same year will also fit)
Does anyone have any advice on how to either repair this tank or a source to find either an original or after market tank for this year/model bike? My hopes is to turn it into a cafe racer so it doesn't necessarily need to be an original OEM tank.
Thanks in advance for your help!