FWIW, I've known nobody who's had one of these trucks and claimed the fuel mileage was any good. Most are in the double digits, barely. BB or SB.

But doing some quick math, I'll base it on your claim of 9.3 mpg average, and a 110 mile round trip, with 1/3 of it in heavy traffic. I'll assume that means a mixture of stop and go, and varying speeds, etc. That would be about 37 miles heavier driving, 73 miles straight highway. If we assume 6-8mpg during heavy traffic, typical for any cammed BB car or truck, that translates to 10-13 mpg highway. Not atypical for a BB pickup. Many members with BB cars struggle to beat that mpg.

I think if you were to step down to a stock or near stock cam, you could see a 2mpg increase across the board, likely more noticeable during your heavy traffic portion of your commute. An overdrive transmission may gain you a mpg or two on the highway, nothing during the heavy traffic portion.

IMO even if you changed a SB, efi and overdrive, you won't see much more mpg that what you have. If it helps at all to put things into perspective, we took a 97 ram 1500 5.2 4x4, no lift, stock tires, on a 3000 mile round trip. On flat level ground at near sea level elevation we got 18mpg if we kept it at around 60mph or less. Upping to 75 dropped us to 13. Once the terrain started to get hilly even in the slightest, we couldn't break the 15 mark anymore, regardless of speed. That's with EFI, overdrive and the improved aerodynamics of a 90's ram, perfect weather, we drove straight through so no cold starts or warm-ups.

If you're making that 110 mile round trip either way, this is simple the wrong vehicle for this application. Based on your driving habits I can't see you being able to improve your average by more than 2mpg. Is that enough to make the difference between this vehicle being viable and not? I would imagine either way you will have to get used to buying gas and think about putting in a slip tank to extend your range.