Where to put water temp probe and oil pressure gauge on engine?

I assume you want to fit up the new guages as well as run the originals?
The oil is easy.
The standard pressure switch is at the back of the block near the dizzy.
Just plumb in a tee piece fitting to accept both sensors.
The std water temp sensor is in the intake manifold near the thermostat.
If your heater is disconnected you can put the aftermarket ssensor in the heater hose hole.Some aftermarket manifolds such as Edelbrock Performer have additional drillings in this area you could utilise.I've seen a bome made adaptor tube fitted to the bypass hose but this would give the wrong reading IMO.I've also seen them plumbed into the drain bungs at the side on the bottom of the block.Otherwise you'll need to driil and tap a new hole in the water gallery at the front of the intake manifold somewhere near the std location.Or you could tee piece the heater hose fitting.