I agree with Tom and Gary. The problem with metering a scene (sure, you have to start somewhere) is suppose you start with f64 and then extrapolate the reading out to your f333, or whatever. Even a quarter-stop anomaly in your initial reading will be grossly exaggerated by the time you get to f333. That incorrect reading will now be compounded by reciprocity failure.

I think you will get better results sticking with the same film (Tmax 100 is great) and the same developing scheme, and keep a few notes on light conditions (bright sun, hazy sun, etc.). This will get you close very quickly.