uTracer? Ronald's electronic project site
I built one to do just that, so I can model the actual tubes I will be using. It's a quick and easy way of generating models. If you use the Derk Reefman's "Extractmodel" you get Koren & Derk parameters for your tube. You can also chose the measurement range to get a best fit for your tube operating conditions so you can do some optimisation that way.
I have done some parameter extraction for folks who have sent me tubes to measure, it's not a "service" but I am happy to do it FOC because that way I get to learn more about tubes
In my amplifier all the 6 Tung Sol reissue 6SN7 I have gives much lower distorion in my amp than any other 6SN7 I got. I think the difference should be visible also when tracing the indiviual tube curves..and comparing . Something is special with the TS 6SN7..

Best regards Balle