IMHO your probably going about it the hard way by trying to merge the 94 chassis/frame and driveline INTO the 71, instead leave the 94 chassis and driveline alone, de-skin the required outer structures of the 94 and "hang" the 71 cab and front end sheetmetal on the de-skinned cut down 94, the bed is the easiest part to swap over, but by hanging the 71 sheetmetal on the cut down 94 cab and inner firewalls you can retain the majority of the 94 interior dash, steering and related underhood driveline and electrical systems, let's face it the 71 steering systems suck in function and design along with a lot of the other 71 driveline maladies