Hi and welcome to SN. You might can find specs to the mast on this site... Columbia T-23 Specifications
If not you could search some sites online such as sailboatlistings and find someone who is selling a Columbia 23T and ask them if they can take a measurement of the mast for you.
Although I never ordered from JSI I am sure others have, they can build a custom mast for your boat... Sailboat masts for every size boat
Another option is you may can find someone selling a used mast, I would think anything for a 22ft to 24ft boat might work.
Hope this helps!