[dsraven]

before you get all wired up and cut stuff apart. do a cross dimension on the stock part of the frame. from corner to corner so to speak. the front is already lopped off so pick spots on the original part of the frame that will be the same on both sides and use a non stretchable tape measure. some fiber tapes will have some stretch to them and some regular tapes have a movable tip because the rivets allow that. in that case the dimension can be off whether you pull on the tape end or push on the tape end. anyway, long story short, be sure the original part of the frame is square FIRST. next, block it up at the rake angle you want. check that with a digital level because the old bubble levels are only gonna get you close and also depend upon the angle that you are looking at them. a digital will get you within a tenth of a degree if you want. a digital torpedo level can be placed op top of a 4 ft level or some other straight edge and they usually have a magnetic base area. check the frame side to side and block it securely. next drop a plumb bob to the floor and put some marks down from identical places along the original frame on both sides. do the same from identical spots on the clip. now use the laser on your digital level, or a string line, to connect the dots and draw some lines fore to aft that will extend the original frame lines out past the front of the truck. now see if the front clip is parallel to your original frame or not and also see if it is centered side to side by comparing the drop points from the clip to the original frame lines on both sides. draw a line across at 90 degrees to your original frame and measure dimensions from that line to the drop points from your clip as well so you can see if it is square with the original frame. once you figure your clip is square then use the level to see if the clip is sitting level across the lower control arm pivots, fore to aft. the clip needs to be sitting level and at the ride height it was made for in order to have the suspension and steering geometry work as intended. I usually block the suspension at ride height , with the full weight of the complete car on the suspension, with some threaded rod through the shock mounts before I take the clip out of the original car for that reason. the springs can be adjusted later with the full weight of the new vehicle on the clip in order to keep the suspension at it's intended ride height, or at least close.
thats just what I would do. it's your truck, you decide. you need a good foundation to build on so get it right the first time. again, my opinion, your truck.