Walt:
I'd say as close as practicable to the exhaust port while still allowing easy access to the thermocouple and welding the boss in to accept it.
On diesels, you always locate the stinger on the hot side of the turbo.
I don't know what brand of probe (stinger) you have but there stingers come in various response rates. EGT Technologies sells all different probes as does ISSPRO.
At least you are supercharged and not turbo'd. A broken stinger tip will destroy a turbo, right now.