It's always nice to see a new truck project. As far as the chassis goes, check out the pictures in my build thread.
https://lateral-g.net/forums/showthread.php4?t=7505
It shows the chassis I am building along with a good low buck jig to build the chassis.
To start you need to decide what you want in the end. A street truck, a track truck, both, etc. Then go from there asking questions of yourself and then answering them. Yes, you will be talking to yourself shortly. What size wheels and tires, what ride height, air bags, coil overs, rack and pinion, front steer, rear steer, etc............. Once you decid on all this, it just a matter of connecting the dots. If you try to figure this stuff out as you go it will take forever and cost twice as much.
Next, a good place to start is measuring the existing chassis. This can be done easily with no disassembly. Get the truck up off the ground far enough for you to crawl around under. Use good stands. Make sure the truck frame is level front to rear and side to side. A 4' carpenter level does a good job. Then if you have a level floor start measuring all the important parts. Body mounts, suspension hanger points, rail heights, thicknesses, etc. More data is better than too little. If the floor is not level go to sears and get a cheap laser level and use it as base point. Measure from that laser line to all your points. Make a little sketch with all the points. Then your engineer can make a sketch of the stock chassis. Then since you have all your earlier questions answered plunk everything in and stay within the envelope of the origianal and everything should fit. Granted this is an over simplification but should get you going. Dive in the water's fine. You will love this site, these people are top notch.
Hope this helps a little.
Good luck,
