Hi I agree with Grigg about staying with a 6 .I have a 235 in my 52 1 ton panel - I went from the 5.14 rear end to a 1 ton Chevy 3.73 rear axle and the 235 pulls it just fine and that's with a junk 4 speed non synchro trans that is stock in it .There is a LOT of nice High performance and engine dress up stuff for the sixes .I have a 1948 2 ton flatbed truck with a 216 6cyl in it ,I drove it from Atlanta to Dolan Springs AZ and back last year 4930 miles total .It only does 45 mph that's 3500 rpm's max .I've installed later Chevy 6 HEI ignition and 80's Dodge 225 slant 6 1 barrel carb. converted to 12v,KIA bucket seats ,dual circuit master cylinder with modern vacuum booster and one of the best mods was installing the 3/4" thick horse stall matt from tractor supply, combined with some insulation for the floors .Even at 106 degrees I had no heat coming through the floors .It goes ,stops great,It's my daily driver .
My long term plan for my truck is starting a small transport company ,I will go to a Chevy 250 six ,long tube headers,5 speed NV4500 Chevy diesel trans,and a higher geared rear axle ,also I have a 48" Peter Built sleeper (will require 52" frame stretch)I'll be happy with 60 mph .
And if you go to a V8, a 283 with a fuel mileage camshaft ,TBI fuel injection conversion(early 80's GM fuel injection )A set of Dorman Products Corvette 2-1/2" Ramshorn cast iron exhaust manifolds ,a good 5 speed trans and better geared rear axle ,I've heard talk of high teen's to the lower 20's for mpg
PM me if you have any questions I'll send you my tel if you want to talk .
Good Luck Paul
Some 6 stiff
http://www.inliners.org/http://www.langdonsstovebolt.com/https://www.cliffordperformance.net/http://www.hamiltonfuelinjection.com/
