Water pressure gauge question

[proprider]

On a 2.0 liter V6 mercury, where is the best place to get the water pressure from for the gauge, and what type of tubing is recommended. Thanks in advance

[rock]

Top of the block. Any tubing with a 50# burst strength or better.

Rock

[proprider]

Thank you!

[Merc 2.5]

430499
Should have similar fitting

[proprider]

Found the plug on the top, removed it, and installed the new hardware. Thanks for all the help!