I bought two Autometer gauges, one mechanical for oil pressure and the other is an electrical temp gauge. The electrical temp gauge has a wire that is connected to IGN or ignition and both of the gauges have a red wire for lights on the gauges...Is it acceptable or can I connect the light wires together with the temp red wire and run them all to the IGN post on the fuse box or should only the IGN wire from the temp gauge be connected to this post and have the wires for the lights connected to another location?

If you run all three to the IGN then the lights on the guages will be on whenever the key is on. The way I wired mine I ran the guage light power to my other dash lights so 1) they were only on with the headlights and 2) were connected to the dash light dimmer.

That sounds like the way to go...where did you tie into the dash lights?

any gray wire you can find. Suggestions would include feed to console shift quadrant or feed to light on heater control, or spare ilum terminal on fusebox

Its OK two connect the two light wires and the red temp wire to the same ignition source. However you will not be able to dim the gauges. If you want to dim the gauges with your headlight switch you can splice the light wires to the original Heater/AC light wire up under the ashtray. Thats what I did!

It's been a while since I've been under my dash, I put 5" autometers in the dash and then 2-1/8" in the console.
You should be able to tap into the dash lamps anywhere but it will depend on where you're mounting your guages. I think the wire is gray or brown. If you're putting the guages near the console the closest place would be the dash lights near the radio/heater controls.