At first I thought exhaust gas, is that why? If so, will that also cause very low compression, misfire, and possibly burn up valves on the affected cylinders?

Where did you hear/read that a blown head gasket will cause high idle ?

My fault, I should have titled the post "will a bad head gasket.."
It was just a thought that I was checking, and a possible cause to my problem. I was never told that this was a sign of bad head gasket. Im pulling my plugs and checking compression so I can get a better idea.

As for the car and its symptoms:
Mid 70's 318, unknown mileage.
No coolant in oil, no oil in coolant, no white smoke, no black smoke. New plugs, cap, rotor, wires
new timing chain set to default position (no advance or retardation at chain)
new oil pump
carb is rebuilt within last year (by me, so not perfect but clean and set to default jetting.)
All grounds/connections have been cleaned and new wiring from the battery to the ammeter to/throughout engine and back to battery. new voltage regulator and Ballast resistor.

It is hard to start when cold, needs starting fluid, but once running for awhile, it can be turned on and off for hours and start right back up. it idles high. Given throttle with no load, it revs up fine with no problem. No clicking or rapping. But, under load, say driving 20 or 30mph, it starts to run a little less smooth, and if you gas it hard under load, it misfires and shakes but still accelerates

Is the choke adjusted correctly? What's the timing set at? Did you adjust the air fuel mix screws on the carb? Have you turned the idle screw down to see what it does?

Have you checked to make sure your choke is working properly?

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Given throttle with no load, it revs up fine with no problem. No clicking or rapping. But, under load, say driving 20 or 30mph, it starts to run a little less smooth, and if you gas it hard under load, it misfires and shakes but still accelerates

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This sounds like a fuel-related issue. Revving the motor out-of-gear is very little load on the motor and the fuel pump. If the car can rev nice and cleanly in P or N but struggles to do the same under load (in-gear), I'd say something is starving the motor of fuel. This could be a weak fuel pump and/or gunked up carb. I have had some fuel pump issues and when the pump is partially failing, you will feel a bucking/surging while you hold the accelerator steady.

Timing could also be an issue here as well. Do you have a timing light? If so, get your initial timing (idling in-gear). Does the engine ping when you romp on it while driving?

As stated before, you might want to try and back out the idle screw a tad to see if you can bring down this high idle. A timing light would help here as well so you can get an accurate RPM reading while you do this.

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No coolant in oil, no oil in coolant, no white smoke, no black smoke.

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This kind of discounts a blown head gasket as that would likely cause coolant in the oil and/or white smoke from burning coolant. Black smoke would indicate a super rich condition and/or weak ignition.

Keep the information coming!

i had a 340 blow a gasket out where the lifters are, ran perfect but sucked oil from the lifter galley smoked like crazy.

How sure are you the timing set is in right? Your symptoms are of an engine with retarded camshaft timing. Choke would either start right up and then be a pig, or be hard to start and then run well.