Low power only 70% rpm and has 85# psi compression Told by dealer needs carb rebuild

Darrell link is to a trouble shooting chart, may help in your diagnosing problem
http://www.tecumsehpower.com/CustomerService/BSI.pdf

With the decompressor active, nominal is 85 - 90 psi. At 62 psi, you have a top end problem. Try dumping a bit of oil in the cylinder and re-test. If the pressure rises, you have a ring seal problem. That sounds like an top end rebuild.

30 psi compression can be rings valves or push rod damage

A new engine would be about 180 psi for each cylinder. As the miles add up and wear occurs, compression will get lower. The important thing is that compression is even and balanced-lowest compression reading should be within 75% of the highest cylinder's compression. Some Toyota engines had a minimum allowable compression of about 135 psi, but if compression is balanced, you could have average compression as low as 125 psi and engine would still run good, some loss of power but still acceptable, and oil consumption would not be that bad.
If cylinder compression is below 120 psi as an average, you should be looking into a rebuild event-rings and valves need attention. If any cylinder is below 100 psi, it may not even fire, certainly will produce no power, and could be a head gasket failure, very worn rings, or valve problems.
Remember the important thing is to find compression readings that are very close to each other. I have an '87 Sentra with 75,000 miles(true!)-lowest comp. is 160, highest is 165 psi-runs great, good power. Also a '79 Datsun pickup (with god only knows how many miles-about 200,000 maybe). Compression is about 125-135 psi, fairly well balanced-noticeable loss of power, very little oil burning, still runs fair to good-dependable, at least.
That should give you an idea of what to look for. Good luck.

Absolutely!. The dealer shafted you, if he told you nothing was wrong. 80 psi leakage out of exhaust (valve,;;;where else?) is a dead give-away: You need a good old fashioned VALVE JOB. Your exhaust valve, see, is not seating properly, not sealing as it should. It leaks, bigtime in your case, so compression is low, unburned gas escapes out the exhaust (You smelled it!), no power from that cylinder so it idles like ****, and will try to die, and of course, mileage suffers. Sound familiar, Robin?
Now of course the dealer knew what it was. Apparently he didn't want this time-consuming job. All he wanted was his in the door and out money. From the shop mechanics point of view, a cylinder head job is a relatively low paying and time consuming job. But there's no excuse for somebody not telling you that you need a valve job. Take it somewhere else. It's gonna be expensive, no getting around it, cause the head has to come off, but at least it's a whole lot less than an engine overhaul. And just give those figures to your new mechanic-the diagnostics are all done. Good luck.

180 psi is good, but depends on the life of the engine, if yours is 150 psi all the rest of the cylinders have to be within 20% of the highest compression cylinder, so your allowed 120 psi on one of the other cylinders, it takes 80 psi to fire the cylinder anything less it will not fire.

DOES THE CYLINDER HAVE LOW COMPRESSION. IT SHOULD BE SOMEWHERE AROUNT 100-130 PSI AND NO MORE THAN 15% DIFFERENCE BETWEEN THE TWO CYLINDERS. IF IT IS LOW, A REBUILD IS GOING TO BE REQUIRED. IF IT IS OK THAN CHANGE THE PLUGS AND DO A CARB CLEANING AND SYNC THEM.

HOPE THIS HELPS

Low compression will affect the engine's ability to idle. So, check the compression. You need to see at least 140 psi of compression in order for it to idle well. Low compression can be caused by insufficient valve tappet clearance. If the valves are adjusted properely and the compression is still low, then there's internal engine work that needs to be done.
If the compression checks good, then you've either got plugged up jets in the carburetor, or an air leak between the carb and the engine that is preventing it from idling.

You're asking a BAD question in my opinion. I'll explain, and give you a FAR better solution... Compression checks in my opinion are fine for checking from cylinder to cylinder ONLY. If you're within 10 psi plus or minus, you're fine. However, cylinder LEAKDOWN will tell you if you've got an issue. You may have good compression, but any compression readings will not show leaks in the valvetrain unless the leak is pretty bad. I would instead test cylinder leakdown both cold and hot using a leak down tester, a good air compressor with a good regulator, and if you have anything worse than 85% in a leakdown test, use your ears to find the air leak. If the leakdown says for example 70%, listen in the exhaust and through the carbs. If both are quiet, listen in the oil fill hole. Now not only do you KNOW how bad the issue is, you know right where it's at. Intake valve, exhaust valve, or piston/cylinder. the Stick

210 psi at 400 rpm (sea level)