Problem:
1. Gas Guage immediately goes past full and maxes out.
2. Engine Temp does the same
3. Engine has a decent amount of smoke coming off the Headers. I thought it was just burning oil but don't see a leak.. It comes out a bit on top on the back half. Engine runs strong. Just smokes. I put all new seals in everywhere. I am not losing oil at an alarming rate. Just have white/grey smoke when I drive. Ideas?

Both guages worked great and normal before the engine swap (efi engine in place of the original 78 block)

 

Hey Scott,

Is this as soon as you turn the key on? Even before the engine's started?
This shouldn't have anything to do with the engine since this is a signal from the gas tank straight to the dash. However, maxing out is indicative of a short. If it just wasn't getting a signal, it'd stay on empty.

Same as above. If this was just the temp gauge, then I'd say the signal wire from your temp sensor is shorting out. But since it's both the gas and the temp, then you have something else shorting out your gauges. It's very hard to say what.
But go through your wiring in the engine bay and see if something's not grounded, two bare wires are touching, or something's not hooked up right.

How many miles on the swap now? Usually "first start up" smoke will burn off pretty quickly. But if you have continual white smoke, then you're dripping oil from somewhere. Maybe an improperly sealed valve cover. Even a tiny drip that'd take months and months to show up on the dipstick can create a lot of smoke. The other thought is that you have leaking valve stems where oil is dripping into the cylinders and then burning up, but you'd have to also have improperly sealed headers to see the smoke, and you'd probably be able to see it at the tailpipe.