I have a lot of experience with a 14" Delta cast iron BS. I've done a lot of tension measurements as well. With a high tension spring it can comfortably apply 12 ksi to a 1/2" blade. If you try to apply more the frame will deflect and throw the upper blade guides out of alignment as the frame bends. You want 20 ksi or higher on a carbide tipped blade. Save your money. Also, if you put a wider blade on that saw the tension will go down proportional to the increased width and there will be no increase in performance.

The best you can do on these 14" cast iron saws for resawing is a 1/2" x 3 or 4 tpi blade. I cut a lot of 10" veneer on mine so it's possible. The key is a sharp blade, a really good setup so that the blade cuts straight, and a slow and steady feed rate. FWIW, I found the Woodslicer to perform very poorly. Bimetal blades are my preferred choice for resawing on that saw.

John