How old is your Lexington?
Unless it is modified by a previous owner with a different tone ring & rim, your rig should already have the HR30 Ring & Huber engineered rim in it which is what gives it the 'Truetone' designation. Perhaps the oldest Lexington model didn't have the 'Truetone' setup, so I may be wrong, but I thought they have always had the HR30 Ring & Huber Rim installed.
A few years ago Steve did make an adjustment from his original ring based on very extensive research, resulting in the HR30 tone ring he uses now. It seems to me he now refers to his original tone ring as the 'Vintage' tone ring. Steve offers another tone ring, the Huber 844 in his Workhorse model. Depending upon your banjo model, Steve will upgrade and he offers a trade in on the other Huber rings toward the Truetone setup... this comes at a very reasonable price considering the tone difference you will enjoy.
Huber is fantastic about allowing each buyer a great selection of personal modifications or customization with the order of a banjo, so every Lexington is not the same in various options, but the Truetone should be consistent unless otherwise modified. If your Lexington is gold plated it will provide a great mellowing to the truetone setup... very nice.
I'd suggest firing an email off to Steve as he & his crew are great about answering questions.
http://www.huberbanjos.com/contact/ for the web-form email or straight to the team with firstname.lastname@example.org
Hope I am correct in the info I am sharing with you, and I also hope it is helpful.