In my opinion a good camshaft grind you are selecting for mileage and torque i have a couple in mind and i will list the grind specs and reasons why and i will not complicate it as some people like to do.......
1) 212-216@.050 with a valve lift with 1.5 rockers .440-465" 112 LSA. This cam will have a rpm range from about 1500 to 5000 .....keeping a LSA at 112 will increase idle vacuum and smoother idle....good heavy duty towing torque cam......now you say you want to run 1.6 rocker arm ratio....the only thing i can suggest in not running a longer ratio is that fact that you may need to alter the push rod holes in the head and run guide plates cause of the change in geometry.
2) 200-215@.050 lift at around 420" and anwide LSA of around 122-115 degree....by keeping the lsa's wide you are decreasing the overlap period wich increases vacuum at idle and smoother idle....running a tight LSA 106-110 will move the power band down to the middle but will result in a poor idle quality and low vacuum......I hope this help because camshaft selection is a critical one especially when you have 5000 pounds to move. Both these grinds can be custom ground by any cam grinder...and fine tuning for your specific needs....I buy all my camshafts from a custom grinder who is local to me.....for both my race car and my towing vehicle so the top cam is what i have in a 1980 1 tonne dually 400 sbc.....pulls hard pretty smooth idle and tonnes of vacuum for power brakes.......its a real stump puller and i get good economy out of it as well.......hope this helps and i think its pretty friendly worded........