Before getting to far you need to determine exactly what your motor is. It could be the stock one or one that was transplanted into your truck already. You need the casting number and the suffix code off the block to find that out.
Casting number info here.
https://www.mortec.com/
Suffix codes here.
http://www.nastyz28.com/decode.html
Once you get that info then you can plan your motor.
Then if all turns out good you’ll need to tear it down enough to measure the piston bores. A motor that’s been already bored .060 already and needs to be bored more might not be useable. You’d need to find another block.
A little research is time and money well spent!