Eric,
A long time ago, in Northern France, someone (not a dealer) offered to me an IR34 helmet, complete, marked and of course with the famous scroll on the plate. It was... a 1860 model. The price was about $ 1000.00 (at the current exchange rate; it was in fact 6000.00 F); I thought it was too expensive and I did not buy it. What a mistake!! One of my few regrets since I have been collecting...
Bruno