That truck doesn't have cats so just run the oils that have the zinc/etc stuff and you'll be ok----There are some metering rod changes for the carb that will help and one big option is to just turn the air cleaner top upside down so it doesn't restrict the flow--------correct timing curve on ignition and hopefully you do have dual exhaust????

With the weight of the truck there isn't much that you can do to get where you want to go with the smog era engine altho a change to a complete drop out of the more modern ones will give you EFI, roller cams, ECM control -you'll just have to do a fuel pump and exhaust system and then you will get in the upper teen milage with much more seat of the pants acceleration------