BB provided the burner which he got out of an old hot water heater somebody put on the curb. I modified it to use a pilot/burner valve from an old central heat unit (don't you dare say pack rat!) and, Viola!

I installed a "T" fitting and a gas cutoff valve in the hot water heater closet on my carport. Bearing Service (North Market) provided 1/2" FPT quick-connects and 6 ft of 1/2" MPT flexible gas line.
My main concern is that the natural gas burner be at least as powerful as the 10" propane banjo burner I've been using, so last Sunday I mounted the burner and did some testing.
Prior to modifying the propane burner stand I measured 2.0 gal of tap water, put it in a 6 gal Vollrath stainless steel pot, took a temp reading and slapped on the lid. Then I fired up the propane banjo burner at my usual boil setting and let the water heat for 10.0 minutes. At T + 10 I turned off the gas, removed the lid, and took a second temp reading.
It took about an hour to dismount the propane banjo, fabricate the supports, and mount the NG burner. Then I repeated the above experiment. Here's the numbers:

If you can decode the spreadsheet you will see that the NG burner is roughly 17% more powerful than the 10" banjo. I think I've got a winner!

Charlie