I haven't worked with that particular carb, but I looked up the basic specs and info in the Holley catalog. It's classified as a "non-emissions" carb, so that is good - I've found the "emissions" carbs can tend to be tricky to tune, and looks to be a decent carb for your applicaton. One difference I saw between your #80457 and the basic #1850 is the #80457 comes with the "black" secondary spring, which is the heaviest, and the #1850 comes with the "plain" spring which is right in the middle. Normally a heavy spring would be what you would want with a heavy vehicle ( like a 1 ton truck ), but in your case with a slightly warmed over engine you may want to consider trying a spring change eventually - but FIRST - have you done anything with the ignition curve in your distributor? That is where I would start my tuning. I've found ignition and carb tuning go hand in hand. Those '70's distributors were set up with the factory emissions systems ( egr valves, air pumps, etc. ) in mind and focused on passing emissions testing regulations and gas mileage, and not what we would consider performance. If your distributor is original, or even a parts store replacement, I would start there. Check what your total timing is, not just the initial timing. Peek through the little window in the distributor plate and look if you can see what advance slot it is set on, there should be two slots, one being used with a small tab visible in the slot and one not used. There will also be a number stamped near the slot, something like "18L" for example ( there are multiple possibilities ). With the distributor installed on the motor you may have to turn it over slowly by hand until you can view the advance slot. There are also springs in the distributor advance mechanism that control the "curve" that come in different calibrations. To make the best tuning decisions you need all the info on your baseline you can find.
