SB Stroker - What Cooling System?

Swapped in a freshly rodded and cleaned 26" 3-row OE brass and shroud. The guage is at 230°-235° on the street and highway and got to 245° when I got home and let it run for a minute.

???
Bad fan clutch?
Blocked water passage?
Inaccurate guage?

Timing is 18 initial, 38 total, all in by 2600.

Converter is TA Tight 10" rated at 3500 but with my 3.23 rear 75mph is 3200rpm.
I am running the trans lines through a plate cooler before the radiator.
I might say converter building heat but the 1700rpm Dacco did the same thing....WTF?