Thanks Billy. I found it at my local flea market for fifty bucks a few years ago. Since then I've spent thousands for a complete collet set and tons of other accessories, all by the original maker...Rivett.
I agree - that is a beautiful lathe! Craftsmanship like that will never come out of China.
Your tool holder will work fine for the carbide bar I cited. Yes, Kennametal owns Circle Machine now but CM products are still produced. I would not recommend buying this bar retail; too expensive. Wait for it to come up on ebay and buy the bar and inserts there if you are interested. If I could only have one bar I would buy this one for the scale of work your lathe can handle. Used correctly, it is extremely accurate and will serve you well.
Nose radius on inserted tip boring bars are extremely important, especially on smaller lathes. Yes, it is the radius on the cutting tip of the insert and the size of that radius will help guide your depth of cut, feeds and speeds for both roughing and finishing passes. The geometry of the bar, the insert, and the nose radius has to do with minimizing or accommodating the cutting forces inherent in the boring process.
I'll contact you by PM later to clarify this a bit more.