[flyingtim01]

You do have a booster on that truck - but it's not a vacuum booster like you're probably used to seeing. Your truck was a diesel from the factory, which makes no vacuum to supply to the conventional vacuum booster. It has what GM calls Hydroboost, you can see the Hydroboost unit behind your master cylinder. Instead of vacuum assist, you have hydraulic assist power brakes - the hydroboost is driven off the power steering pump.

Now that you've swapped in a gas engine in place of the diesel, you may want to also swap in a conventional master cylinder and vacuum booster, just to simplify things for yourself.