In your original post you said you DID NOT want to touch a drivetrain build until you get a rolling chassis. IMHO the drivetrain is the most important part of a chassis build.
I did not hear you say what engine and trans combo you will be using. TP chassis could come with any combo, S/B Chevy or B/B I let the engine/trans break line be within 1 inch of firewall. That gives you room for the distributor [HEI] and not interfere with firewall. Also lets you get to the tranny bolts to pull either engine or trannny separate as well as have more floor room with a smaller trans tunnel.
Ford engines are a little trickier, as the bellhousings are different in size and must be Mocked Up with what engine/trans combo you are/will be using. You will also lose a lot of foot room with Ford, Dodge, Crysler, Buick, Olds, or odd ball engine/trans combos. I think there is an article in TECH INFO about engine lengths and diminsions here or on another t-bucket site.
RPM said the body was 58" from the kickup to the firewall. Measure from kickup 58" on both sides of frame rails and mark where the firewall should be. The diferance in the lengths of the two bodies is what will need to be added to the frame. Call Wintech for the dimensions of thier body, I think it is the same as T/P. Hold steering box on frame in front of firewall mark and leave enough room for a wiggle u-joint to go from input shaft of steering box to steering shaft coming through [said] firewall at the desired angle . Steering angle is CRITICLE when mounting box to frame so seat height and width can be measured. It will be a guessing game without the body. Also engine height, length and placement in frame will affect steering box location as the box will be under the back header tube.
IMHO you would be better off putting things on hold until you get all the major parts on hand, as I know from experience, it will cost you more money to fix the mistakes after you realize things don't fit, and ruining a purty powder coat job. Most on here will tell you that have built their own bucket, that they pulled it apart a bunch of times [as many as 10] to get what is supposed to be right, look right, feel right, etc. BEFORE painting it!! Even buying a KIT does not guaranty anything will go right the first go round as most parts are FITTED for each bucket and all parts are not usually included. Most people build to a specific look or style, so eveything will be done on a [as come as you can get parts ] and each part fitted to the bucket.
I wish you well and don't mean to be condesending or anything, hope you will keep asking questions as there will be many more, I guaranty it.
Bruce