Shortening the frame

[Bowtie67]

I havent been on in a while but I am going to redo my 67 back to a stock frame and front suspension. A while back I made a custom frame because of an afternarket weldin front suspension to my orginal frame that I put in it that had nothing but issues, constant bushing replacements, bad handling , and even had to do custom headers (Vender is now on this forum, you can do searches under my name to find details rather then me getting back in to it). Anyways when I built my custom frame I even pro streeted my 67 short step, now I want to go back to a stock frame and suspension even though it still drives and handles well. I picked up a really nice long bed frame and need to shorten it and I know I have seen posts on this in the pasts but unable to locate any info on this and any upfront help would be appreciated. I probally wont be starting on this real soon as I have a 48 Chevy Fleetmaster Coupe I am just finishing up and recently started on a 50 Styline Coupe with and for my son. Thanks