Reducing the wheel OD (rim and/or tire) is very effective, except that it ruins ride quality, ground clearance, and traction, and looks too import for most people with classic musclecars.
Here are 26.5" (about average) OD tires on an import.
Front 245/40-19 on 8-1/2 X 19
Rear 275/35 on 9-1/2 X 19

We did a similar swap in my Duster years ago....also had zero change. LOL.

Hey, I resemble that remark!

^^^^ THIS ^^^^. Not specifically fuel supply, but the law of a chains weakest link. ie: If your fuel supplies limits your combo to 10.80, and you make improvements elsewhere, even if they were effective improvements in their area, the limits of your combo will most likely still be 10.80 because of the fuel supply system. Now weight improvements would seem to be the exception to this because less weight should ALWAYS be faster, but it still doesn't always seem to work. I know what I'm describing seems to be just stating the obvious, but think most of us still tend to ignore the law of the weakest link. I know I do.

It would seem to me that key to making effective changes is to continuously know WHERE your weakest link is. And that's not always easy! Again, obvious.... right?

To the OP: I made the move from steelies to lighter rims on my car and saw about a tenth improvement, but I changed tires and gearing at the same time, so....

that thing is cool.. anyway. My old 67 Coronet (3850lbs) had heavy cragars all the way around. I replaced the rears w/ 15x7 stelies and the fronts w/ 14x5.5 steelies with smaller tires. I believe the the total savings was 45lbs up front and 30something out back. The car ran 12.90 w/ the Cragars and 12.90 w/ the lighter wheels w/ the same MPH (104)

cragar ss wheels are good looking, but the 15x4's that i weighed, including center caps were just a tad over 23lbs. each ! a factory 5.5" steelie weighs in about the same at almost 24lbs.

The absolute overall weight of the wheel & tire combination should, of course, be as light as possible without losing function since it's 100% unsprung weight. However, this has no more effect on acceleration than the same weight removed from the roof or the driver.

A valid yet inexpensive test of rotational inertia (how much power is used to spin a wheel up to speed) could be a coast-down test.
Measure the actual diameter, from this calculate the speed in RPM to turn a specific MPH. Example: a 26" OD wheel = 81.68" circumference, or 6.807 feet per rotation. At 2,000 RPM that's 155 MPH.
To allow different diameter sets to be compared, the second T & W combo should also be spun at 155 MPH (not the same RPM unless it's the exact same OD) for comparo. Two sets with identical weight and OD may have different moments of inertia depending on where the weight is located: rim or hub.
Record the time in seconds to stop from speed, the one with the shortest time is the lighter MOI (duh). No, there is no easy math to say how much, just which wins.

Did I leave something out?