Peter said, "Originally it had appeared that calibrating my meter might mean that I’d turn my ASA all the way down to .32—it is of course presently turned to .68. So if I dialed in .50 (Does that sound right Lee?) on my ASA dial the film would be exposed slightly longer AND my development time would be shorter yet i.e. less than 5m45s."
Yes, ei 50 should be about right. IF you are looking to print on Grade 3 paper then yes the development would be a little shorter. This is FP4 and I think this film is a little contraster than its faster sister HP5+. Go ahead and make a contact print sheet of the frames. Set the enlarger height to an 8x10 and leave it there for all the tests and subsequent printing. Use a grade 3 filter. Make a test strip in 2 second increments across the paper. Where the film is in contact with the paper and really look closely at the blacks in zone 0 and at the film edges. Find the first "real"or Maximum black and use that time for the contact print. Now you have a strip that should represent all the zones. If you are losing some frames to either too black or too white, look at the test strip and reevaluate your choice. If it is too black then adjust your time shorter and conversely for too white lengthen the exposure time. Remember that the zones above zone VIII will in all likelihood not show anything but white. This is to be expected and ok. There should be a difference in Zone III and zone II and a very slight difference in Zone II and zone I. Make the next print with a grade 2 paper after you run that Maximum black test again. This will show you how your camera and film and developer will react with the paper and the enlarger. good luck!
I think I might be tempted to shoot a roll of "real" images and develop them to your new time shot with the ei of 50. Use the enlarger height you were using and use the exposure time that you found for the contact prints. Let's see what happens now. Try it with the grade 3 time and grade 3 filter and then use the grade 2 filter and grade 2 time so be sure to note them and write them down. When making the real photos if a person is involved make that skin zone VI if that caucasian. To do that meter the skin and open up one stop. again good luck. You are now one your way to discovery of photography at a very different level than you were 2 weeks ago.