While you're studying, you also can (a) figure out what year of 350 you have from the casting numbers and (b) go to the GM Heritage pages for a bunch of information (example:
https://www.gmheritagecenter.com/do...hevrolet-Trucks/1969-Chevrolet-Truck.pdf) Change the year number in that https string to match the date of your engine...let's guess for example that you have a 350 produced in 1975. Then go to that year's info and you'll discover the 350 in 1975 produced 250 lb/ft of net torque at 2400 rpm...which is a pretty nice torque curve for what it sounds like you're trying to accomplish. It starts to flatten around 2000 and by 2400 has hit peak and begins the downward trip. If low rpm/higher torque is your goal, the way the 1975 350 was set up could be good for you. But if you look at the high torque option for 1969, you'll see the high torque engine without pollution equipment produced 355 gross or 310 net lb/ft at 2400 rpm with a curve that looks about the same as the one in 1975. More torque at the same rpms. And while you're on the 1969 pages, look up at the optional engines for the El Camino and you'll see the Turbo-Fire 350 had higher compression and was set up to produce a gross torque (I didn't see a net figure) of 380 at 3200 rpm...a move toward hot-rod status (7% more torque but at 33.33% more rpms--and clearly that won't help your gas mileage). And you'll learn if you study this stuff a bit in 1969 the overdrive 3 speed was available but only on C10 trucks and only with a 4.11 rear end ratio. My point is this: we have no idea what the person who set up your engine did, what he used, what he was trying to accomplish. However, if you want a little power and you still want gas mileage, you might find a nice compromise with a stock GM camshaft.
