tune your truck first

you should be able to open the ecm, pop the chip out, and put it in a chip reader if you wanted to pull the stock calibration off, then tune it with tunerpro, and write the program back to the chip.

it's not the most elegant way like newer flash or realtime ecms but it will get the job done cheap

im pretty sure your truck would already have a 7427 ecm so now you have a spare if you really mess something up

i will tell you tuning trucks that are no longer being used as a truck (i.e. not hauling yards of gravel or towing big trailers) can be very rewarding. the stock tunes are very very limp in terms of both spark and fuel, because if you're driving up a big hill with a ton of stuff in tow, they don't want it to blow up. there is TONS of power on the table.

so a tune for a truck like that would be something like:

- drive around and get a datalog with your aldl cable and tunerpro, maybe bring a wideband with you too. you can use the logs to see how close the stock fueling tables are, and how much you'll need to change them.

- make a first attempt to correct fueling by making some small changes to your VE table, so when you load your new tune you can datalog again and probably get it close to good on the second try.

- spend some time on your spark table. if you have a different cam than stock, you want the 'under load' part of your spark table to be a bit different. timing should advance towards the torque peak of the cam then level off, well, you have a different cam. you can also add quite a bit of timing advance everywhere on the table in general if your fuel quality is good and you aren't towing.

- tune power enrichment fuel. for something not hauling heavy loads, with consistent fuel, you will find peak power near 13:1. new tuner probably target like 12.5:1 or 12.8:1 or something. the wideband will really help with that.

- load your new tune and go and data log again. this time you're checking not just for fuel trims (to see how your fueling is doing) but also watching your wideband to make sure when you floor it, your AFR stays in the safe zone. you're also watching for knock to see places where you might have gone too far on your timing table

- now go back and make a few more changes based on what you see in the logs

analyzing logs can be a bit daunting, i have written software that helps A LOT, can teach you to use it. trimalyzer is pretty good for a beginner, i wrote it because i was kinda tired of teaching new tuners how to analyze logs.