JW - I saw the wiggle words.
Internal combustion engines are amazingly adaptable.
A good friend, that was a Carter engineer, to prove a point, put a 750 Carter Competition Series carb WITH MANUAL CHOKE on a 2000 cc pinto! And made it work, after a fashion. He had to control the choke with one hand, the steering wheel with his other hand, and shift with his third hand!
So it WOULD run!
Another example: if you owned a hayfield in southern Illinois, of several thousand acres, you COULD haul in the hay using a Toyota pickup! But a semi with flatbed might work better.
If your 250 was a fully-modified race engine in a trailered race car, and you left the line at 5k RPM on the dragstrip, the 390 Holley would probably work. But this is the engine forum, not the high performance forum and especially not a race-only forum.
And please take no offense, but "sort of work at some sort of acceptable level" is not in my world. No recommendation.
But to partially answer your question: as far as I am aware, the smallest 4-barrel produced in the USA was a Rochester for the 195 CID Pontiac Tempest. They are quite scarce, and very pricey; and I certainly would NOT recommend one for the 250.
Jon.
