What would you do?

I bought a 97 Dodge Ram 2500 4x4 and know little about its history. My injections pump was diagnosed as dead and I am in the process of getting it fixed. I am finding terms I am unfamiliar with and conflicting information of all sorts. Can you please help me make wise choices going forward?

ABOUT THE TRUCK:
Stock truck.... from what I know, or what I thought.
Stock intake, stock exhaust. Manual transmission.
This is primarily a daily driver. In some instances I am carrying around 500 lb drums, or as many as 3 drums. The other use would be to haul a car trailer with a 5,000lb vehicle on it. I could see myself in the mountains when towing.

PROPOSED REPAIRS:
I was getting about 13.5 mpg. My engine would not start and when towed in I was told my injection pump was bad. I have since sent it to be rebuilt. There was some confusion as to what they were supposed to do to the pump, so they went with the settings it had when it came in.

I sent in the injection pump and the injectors. I was told the injectors were a performance "automatic" injectors instead of stock manual injectors. The injector pump itself was putting out 270cc. After talking to the mechanic he said stock P7100 would push about 180cc, so he pulled back the fuel flow to 235. He also sold me on Bosch +70hp Performance Injector Kit (sku# 1040753B). After some reading I am under the impression these are "marine" injectors which seem to be controversial. Mechanic wanted me to use thin set of washers I think to compensate for the degree difference from 145 to 155 degree spray pattern. I was told this before I knew anything else, so this is just my guess, including whether they are marine injectors?

In addition it was decided to increase the governor to a 3,000 rpm rather than the stock 2,500.

He also told me of two other things he felt would be imperative. Cold air intake, and 4" exhaust to allow the motor to breath with the increased fuel flow. For $300 delivered I got the exhaust and popped for the cold air as well because I believe in the need.

He also suggested boost and EGT gauges, more I can't afford. Given we are reducing fuel flow, and adding cold air and 4" exhaust, I think it should be ok, but I can see adding these down the line. This has just all gotten very expensive.

I'm questioning who set up the motor with 270cc of fuel flow without any other mods to keep EGT's down. Sounds like they should have melted the pistons from what I have read...

I don't know what the timing is presently. And could the turbo have been "turned up?" Or the boost? Not that I know how to remedy or test either of these.

So, what would you do? What should I be checking?

When it comes to gas engines, I know more than most, but diesel is a new breed to me and I don't know the base rules. I'm trying to thin out the fringe opinions and get down to a basic reliable truck with some reasonable improvements to hopefully get better overall performance and fuel economy. I drive pretty conservatively trying to squeak out any extra miles. I think the truck is quite capable stock, but the failure of my injection pump has created a swirl of questions about what I have and where to go from here.

Thanks for bearing with me, if you are still here, please let me know your opinion.