For however helpful in might be to someone else, I want to report back in on what appears to be the final solution to my burner problem. Jon Pacini of Laguna technical support suggested that I continue to reduce the orifice size down to a number 58 drill, which is a little smaller than 3/64ths. . Though I haven't done a full firing yet, with the lid open and at 7 inches of water pressure the flames are now about 10 inches high above the floor of the kiln. The top 1/5 th is yellow and the bottom 4/5 is blue. This seems about right to me.
I want to thank all of the people on this forum, as well as Mark Ward and Jon Pacini, who offered much good advice. The least helpful people were Olympic Kilns Co. In fact, they were the real source of my difficulty given that the repeatedly asserted that 5/64 jet size was appropriate for propane on my kiln .
Thanks to all