If your 283 is a 1969 and up it has a pipe port on either side of the block. Or if you have a modern aluminum intake, there are ports on it. Next best is not water pump, it is the thermostat housing port you mentioned. the other ideas: inside of hose and a piece of exhaust pipe spliced into hose with a bung are last resort and too much risk/leaks, etc. I believe the "T" idea does not provide the intimate contact with "hot" that is required. The "T" will act like a heat sink. Not too many do it that way. Don't even know if the probe will be too long for a brass "T"? Some have put them in the radiator drain hole! BTW, IMO: If you ever do this again, get an electric gauge. No reason to get a mechanical, they make electric that look like orig or real close or you can put a gauge face decal on it. It's just that a wire is much less worry and installation/routing trouble. You are using a relay for the fan, right? Can't you install the A/C and see if your truck overheats first? 5-6 fan blade swap, no other components on the engine, power steering, etc? Florida ain't Arizona. Largo? You're almost on a freekin Island.
