That's not bad considering...a 292 would probably get as bad or a whopping 1 mpg better only cause its a little bigger...less engine stress...dump an ol 5 speed GM trans...oh what was it...Spicer 5 speed? That'd give you another gear. lol Something like .76 OD I think...not sure..it was on that GM heritage site. Not sure what the 292 in my C-10 gets...Wonder if the mileage increased a tad with the 4 barrel, headers, an HEI...they say it should get around 16-18 with those mods...but who knows. lol! Put a turbo on that 250..then when you WOT it from a stop light you be up to speed so fast you will have hardly used up any fuel.
