I would check the water temp with a thermo to get an acurate reading
stock gauges are
my small block runs around 190 with a 180 on hot days and never drops
I just have removed the guts of the stat and used the ring as a restricter and drop it a bit...now it only goes to the 160-170 no matter what
put a spring in the bottom hose to make sure its not sucking flat and try it with a resricter in it maybe
maybe,its where its gonna ride at