low end throttle response is real sloppy
That makes me think the carbs need another going-through. By 'sloppy,' I think you mean they aren't smoothly picking-up rpm's. In my experience, that's usually due to crud in the pilot jet(s). One or more of them.
What does the inside of the gas tank look like? It should be shiny metal everywhere. It may be coated by a prior owner. That probably would appear to be a dull white. Not shiny bare metal. If the gas tank interior is corroded with rusty metal, it does no-good to clean the carbs as they will have one or more of their pilot jets clogged before you finish a tank of gas. There are multiple ways to clean a gas tank. I like removing the electrical connection for the fuel reserve, and putting on a blank-off plate you can easily fabricate from a 1/8" or greater piece of metal. Then fill the tank with 6% cleaning vinegar and check the progress every 12 hours. I suggest putting the tank inside a plastic tub big-enough to hold it, if the blank-off plate leaks. 6% cleaning vinegar can be bought at your supermarket or HD or Lowe's, and probably Ace Hardware or similar. Don't use the 30% cleaning vinegar at full-strength! Yes you can get cleaning vinegar at a variety of strengths. You can also use it again, so save the gallon containers it comes in. If you want to pay $$ for Evaporust, be my guest.
I strain my vinegar as I'm storing it, a fine screen or cheesecloth, to remove any rust particles.
Most important! Immediately after emptying the gas tank of vinegar, rinse it thoroughly, and use an air source like a hair dryer or compressed air and a 1/8" I.D. pipe to blow-dry the tank thoroughly. If you say, "screw that, I'm gonna let it air-dry," by the time the inside does air-dry, it will have already have flash-rust on it! Once you have things dried, use some of that last oil change inside the tank to thoroughly coat the inside of the gas tank. That will keep it from rusting until you can put it back onto the bike.
To return it to service, remove the fuel level/reserve blank-off plate, and drain any oil, That should allow all but a couple of teaspoons of oil to empty. If you're worried about the oil, you can replace the blank-off plate, and throw a cup of mineral spirits into the tank, and agitate it, so that the mineral spirits washes all inside walls of the gas tank. Then remove the blank-off plate, and let the mineral spirits out. re-install the reserve gas electrical sender, install the gas tank, and fill it with regular gas. Hook-up the fuel pump, turn on the ignition, and let the fuel bowls fill. Turn-off the ignition, and use the carburetor float bowl drains, one-by-one, to drain the float bowls. Use a fresh empty container, and empty it for each float bowl draining, so you can see what the gas looks like. I use a clear glass container, and that gives me a good idea of how-clean the float bowl is, before starting the engine.
Use a place outside to drain the gas, and have a fire extinguisher close-by. An 'on' water hose is a good idea too. Do not drain gas near any gas-fired appliance like a gas-water heater. Gas fumes can travel 30 ft. to an ignition source to ignite!
This is one way to approach cleaning a gas tank. You can use electrolysis, but I wouldn't do that inside, or leave it unattended, like leaving it working inside the garage, and going to bed. There are other rust-removal products, but probably none as-cheap and as safe as cleaning vinegar.
Probably after 36-48 hours, the gas tank should be clean, for moderate rust.
. Was really hoping not to tear the carbs back off.
