Fitting a temp gauge to your engine is real simple, you can just undo any bolt on or near the cylinder head at the top (higher the better) and get or make asimple z bracket with a hole drilled in it. you can go buy a very cheap sender and a gauge.
the sender will have a brass end on it and you want this to touch the cylinder head, now this touching the head will earth will provide the earth for the gauge.
just clean the head of paint where sender will touch is best.
fit the gauge in the dash and simply run 1 wire all the way to the sender. another wire will go to 12 volt off your ignition. it realy is that simple.
if you have a light bulb in the gauge that can be simple extra wire from the positive or a switch of your own .
I am not sure about your engine, but later 60 and 70hp have a threaded hole at the top right for this very thing.
here is a pic of the sender on mine with a single wire to the gauges.. as the temp goes up it simply lets more current to the gauge, very simple and very efficient.
now if you want to fit a water pressure gauge as well, then this can simply be from a gauge to the tell tale fitting on the engine.
most people cannot even see the tell tale when at the driving position, so by using the fitting for a gauge is good. you use a t-piece to have both tell tale and gauge but that is not accurate.
her below is the sender attached on mine, but a z fitting can be used, note the single red wire with yellow crimped ring fitting, this is the only wire need to run from engine to gauge, the positive can be run from control box up near the dash or any other 12 volt positive.
this picture show a cheap gauge and sender from a car accessory shop, the only difference between marine and auto is the outboard temp runs lower so not exactly in the middle when running.
mine runs at cruise around 65 degree Celsius and at full throttle around 60, and 70 at idle.
the brass sender came with the gauge, but you have to get wire, very cheap item to buy.
here is a blown up picture of the sender, as long as the end of this is touching the cylinder head it will work good.
some of these come with a z fitting, if not simply make your own.
hope this helps, its a lot simpler than it sounds and take about 15 mins once the hole is cut in the dash for the gauge.
