New T stat & new radiator

Okay, I got all the new parts today.  I installed the new carburetor with the adapter plate and fired her up.  I had a problem with the choke.  I ran a hot wire to the positive post of the choke like the directions said.  For some reason, the choke assembly on the side of the carb got SUPER hot.  I disconnected the hot wire and ran the engine without the choke.  It seemed to run okay with no noticeable difference and the vacuum gauge was still vibrating and jumping around.  I'm going to call Summit about the choke getting hot.  I'll check the plugs and check for air leaks in the day light.  Hopefully this new carb will do the trick when I fix the choke and install fresh plugs if necessary.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

I blocked the choke plate wide open temporarily.  I installed new spark plugs.  I drove the car and it runs much better with the new carburetor.  It doesn't hesitate like it did before.  However, I still cannot get a steady vacuum needle.  I played with the timing today.  If I set the timing by rotating the dist so that the mark on the crank lines up with the tic marks on the timing cover the engine runs like crap.  If I rotate the dist so that the mark on the crank is a few inches below the tic marks on the timing cover the engine runs much better and has a higher, more steady vacuum, of around 16-18" but the needle does rapidly vibrate.  Is my dist in wrong giving me skewed, incorrect timing readings?  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Have you checked to see if the balancer has spun.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

I would suspect a spun balancer ring. To check for this, I made a piston stop from an old spark plug. I punched out the porcelain and clipped off the electrode, then tapped the center of the plug for 3/8NC bolt threads. Just install it like a spark plug in #1 and rotate the engine by hand (remove the other plugs first to make it easier). When the piston contacts the tool, mark the balancer with a marker in line with the "0" on the timing tag. Then rotate the engine backwards almost a full turn until it contacts again and mark it. If the balancer ring hasn't spun, the actual timing mark on the balancer should be 1/2 way between the two marks you made. If it isn't 1/2 way, you need a balancer.
Steve  
Trying to help... 'cause we don't all have to learn the hard way!

What causes a spun balancer?  What exactly happens to the balancer to make it "spun"?  I turned the engine by hand and using mechanics wire in the #1 plug hole I found TDC with both valves closed for the #1 piston.  The tic mark on the balancer was lined up with the timing tag on the timing cover.

Does the dist need to be installed a certain way?  Or can it be installed in any position so long as the rotor contact is under the #1 dist post on the cap, and base timing is then set?  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

I talked to a friend mechanic of mine and I have a good grasp on what a spun balancer is and what causes it.  I am going to play with it tomorrow and see what I can find out.  I forgot to set the timing with the vac advance unplugged.  I am sure that either caused or contributed to the problem.  Thanks guys.  I'll let you know how it goes.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

I tried to set the timing again.  I hooked up the timing light to battery power, coil negative, and #1 spark plug wire, and disconnected the vac advance hose and plugged the carb.  Same problem!  If I set the timing at 10* the engine runs horrible.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.