where is the best or proper place to hook up a water pressure gauge to get a proper reading? also what psi should i be looking for? htm ss24 with n/a bbc engine. thx

The best place is in the intake manifold. You can also hook it up to one of the block drains, but they tend to clog very easily.
Pressure at idle will be 0-3psi and will go up from there. AT WOT you really don't want more than 25-30psi.

Mercruiser installs the pressure sensor for SmartCraft system in the thermostat housing, in the location [square drawing] in this picture on my engine . I have a backup mechanical gauge in the dash too with a fitting and tube plumbed into an existing hole with pipe thread, right next to the SmartCraft sensor.
Pressure like said above is, 0-3 at idle, 10 pounds at 3000rpm and about 25 at WOT with new impeller installed. About 20 at WOT with some hours on already.

I would like to borrow a thought on this thread as well.

Is there such a thing as a electronic water pressure guage?
Meaning to NOT run a water line to the dash?
Run it as a back up from the Merc placement?
Or does everyone have water lines running to the dash?

Never heard of an electric water pressure sender or gauge, other than the smartcraft stuff. Its simple to run a water line to the dash.
The tubing used is just 1/8" plastic tubing. you just have to be careful not to kink it while running it there.

I used a 0 to 45PSI sender (auto parts store) w/ 1/4" pipe threads to monitor H20PSI on my dash my gauges are displayed thru Race Pack. I think it would read the signal on a Oil PSI gauge from Livorsi just the same (Livorsi may already make an Elec H20 gauge). The sender does not know what fluid is bldg the PSI just that there is X amount of PSI there.

Little late to respond but here it is.The Smart Craft system using an electronic device [ sensor] I have in my 6.2's thermostat houising. I have mechanical backup [ 1/8] tubing hooked up next to the merc sensor in the pic I posted.

any 4-20ma pressure transducer can be used with a maretron fluid pressure monitor module (FPM100) and if you have a plotter that will display NMEA data you should be able to see it there, or you can buy a display from Maretron and monitor all kinds of information. Can get expensive but nice to have all the info at your fingertips.