I've done some checking on my 64 Suburban and found I've got a 350 block (3970010) with 3.5" stroke & 305(354434) heads,topped with a 2 barrel carb. Why would this combo be done? Good or bad, runs like a sewing machine & is pulling 21.5" vac at 600rpms. I'm not going to race a 5500 lb. sled but would like to get better mileage, it gets about 13mpg now. Any suggestions?
