Greetings from another Ariogala researcher!
I did look at a listing I have of gravestones in Ariogala compiled by David & Sonia Hoffman in 1999. None are old enough to be of help to you. The two oldest years are 1832 and 1840.
Searching: RATOWSKY / CHAIMSON (Ariogala / Ragola, Lith.)
WALTZMAN / WALZMAN (Ustrzyki Dolne / Istryker, Pol.)
LEVY (Tyrawa Woloska, Pol.)
LEFFENFELD / LEFENFELD (Daliowa/ Posada Jasliska, Pol.)
BOJDA (Tarnobrzeg, Pol.)
SOKALSKY / SOLON FINGER(MAN) (Grodek, Bialystok, Pol.)
BOBISH / APPEL (Odessa)