To make a really good carburetted inline six you've got to have more than one carb. One of the inherent characteristics of an inline six is that you can't get even fuel distribution from one cylinder to another with only one carb as the center cylinders will run rich and the end cylinders will run lean. Two carbs work OK, but three work even better. I'd guess that two progressive carbs (i.e., the primary barrel opens fully before the secondary barrel begins to open) would improve economy as well as performance.
So long as you're not asking for lots of revs that long stroke isn't all bad as it contributes to a nice flat torque curve, the downside being that as revs go up the piston speed on a long stroke engine gets high, which loads the bearings and contributes to bore wear. Some manufacturers got away with long stroke performance engines however, just check the stroke on a Jag XK six, like the old 3.8 and 4.2 units used in the E-type (plus pretty much anything else Jag built from '49-'71 and even after). With the twincam head they breathe well enough, but they
do not like to rev, it was all done with torque. A good mid '60s Chevy 327 with the Duntov cam just loves to rev happily to 6500, overhead valves and all, which surprises people who think of old 'Vettes as sloggers and E-Types as high strung revvers. Maserati also made some really long stroke stuff with the 3.5, 3.7 and 4.0 inline sixes used in the 3500, Sebring, and Mistral, all of which were pretty rapid devices during the '60s. They didn't rev either but with their twincam heads, twin ignition, and from about '62 fuel injection they didn't have to.
I will confess that while I'm not a V-8 guy at all, and not a Corvette guy either, those old "mid years" 'Vettes made from '63-'67 are pretty decent cars. The steering isn't too hot and oh yes they rattle, but the chassis isn't half bad, and a hot 327 with the little Muncie four speed trans is a very nice combination indeed. The tranny shifts as well as a good Alfa, and with the short gearing many of them had you can punch it at highway speeds and not even downshift - it just squats and goes with a lovely V-8 whine. There is a price to be paid, however: I once drove a semi-tired '66 convertible on a 100 mile freeway trip and ate 9 gallons of premium, though I will admit to seeing 90 whenever I could
