Though I've never tried them on a small-block, the old Direct Connection 4782/4783 carburetors are the cat's knees on a big block. I think everyone with whom I've spoken who's run both prefers the mechanical setup. I bought mine when a roommate had factory A12 carbs on his 440 Charger R/T. After considerable tuning he still could not make it run as well as my DC carbs did box-stock (neither engine was stock). It drove him nuts, especially since I paid $225 for intake, carbs, and a "Mr. Norm's" (aftermarket SB Ford) air cleaner.
However, as
@33IMP has stated, ain't no way a carb with both a center-hung float bowl
and a metering block will fit on a factory intake. That was the first thing I attempted with mine. When Holley came out with the new carbs shown in Post #1, I contacted that former roommate (who now works at Summit) about getting measurements. "I already looked. Not happening." I've since found another set of the DC carbs.
While simply using side-hung float bowls seems an easy solution, try and find one for a 2-barrel. To my knowledge, the only Holleys that ever used the required float bowl(s) are the 4782 and 4783, and that was N/S in Holley catalogs decades ago. Everything else with side-hung floats and a straight outlet used a transfer tube. After looking for a few years, I'm to the point of finding a vintage 1850 front bowl for my spare 4782 and figuring out the best way to block the transfer-tube provision. Hokey, but effective.
