Thanks for the tips, everyone. I located a record from the Old Snipishok Cemetery provided by LitvakSIG:

Surname

Given Name

Father

Age

Comments

day

month

year

Town

Uyezd

Guberniya

Type of Record

page

No. on map

 

PREGER

Avraham-Shimon

Tzvi-Hirsh

Gregorian date of death 1776/1777. Nickname: 'Rabbi Shimon Hagadol (the Great)'. Righteous teacher

5537

Vilnius

Vilnius

Vilnius

Snipiskes Cemetery

I am confident the rabbi was Avraham-Shimon ben Tzvi-Hirsh Preger and known as R' Shimon Hagadol. On some trees the surname is being given as Freger.

--
Adam Cherson