Why are 318's low HP and torque?

Hey Guys,

I am planning to rebuild my 318 mainly stock but with few upgrades. I have Bosch 24lb blue top orange tip injectors also Milodon valves 2.02/1.6 (in know not recommended that big intake but this is what I have).

I am all about low and mid range torque, it would be for a 2500 camper conversion. I probably will gain with a new cam (thinking the shortest duration not sure about the lift but 2.02 intake big enough I guess) also new pistons for the best compression.

Rest, I would like to keep it as it is. Any suggestion? Any help would be approached.

Questions:
Would 24lb injectors with 2.02 intake valves be okay with stock lift? Or better with 21lb injector with 1.92 intake valves and high cam.

New cam and shortest duration, what would be the absolute shortest duration ( I want to separate as much as u can intake and exhaust openings) do I need any lift with 2.02 ?

I want a torque monster what will last, not a screaming high rpm racer.

As I said it's a camper (means, I can be anywhere) I also looking a decent guy who would do the job on the budget. It's a slow project I have at least 2-3 month maybe more