If the truck is the 55.1 in your profile you need to make some decisions regarding the entire build plan. The builder is correct to a point as I would have also included brakes as a key first ingredient.
What type of motor will you be using? If a V8 you will need a new transmission, drive shaft, rear axle, springs (or other type of suspension) and the brakes will be covered by the new axle. A 10 bolt from a 70-81 camaro will work for your truck but you will have to redo the spring perches.
There are several front suspension options but only an IFS kit is the sure bet for an upgrade and is worth the initial extra cost. You can subframe it but if you do not have experience doing that type of modification or have limited access to tools and mechanical ability you will find that method difficult.
The very first step is to get the truck out of the ground and see what you have. Is the frame rusted out? What shape is the sheet metal in? What pieces are missing? Anything can be saved with enough time and money but it may be a case where Pa's truck just needs to be parted out and you go find a better candidate. Do not let the emotional side of the equation govern everything. These projects can swallow money like Monica.
