If bolting on the 54 cab to a 51 frame, there shouldn't be any issue there. However, the 54 box on that frame will be a pain because the 54 back end of the frame is lower to create a deeper bed. It can be done but it will cause you major irritation.
Are you getting his cab in this deal too, or supplying your own?

I would also make VERY sure that your friend is competent in his abilities. If the work is not "up to snuff" you may be in for a great deal more work, time and money. Some things to consider for example:
Engine to firewall clearance?
Radiator clearance?
Power steering hookup- rack vs box- does it clear headers? Inner fenders?
Engine/Trans combo angles? Centered?
Good welds, or are "popcorn fart" weld beads layed down?
Pinion angle set correctly on rear end?
Floor to trans clearance?
To name a few...

Now, in my personal opinion on pricing he probably has a lot of money sunk into this old girl. I would be uncomfortable making this kind of deal even with a friend. "Deals" can come back to bite you in the behind. That being said though, you may in fact be on a great path to finishing and you two can sip a couple brews together as it progresses. On the other hand, if you haven't been thorough in your pre sale assessment a resentment could possibly grow. Think of it this way, he's fed up with it and willing to take a loss because it is VERY difficult to finish. Are you ready for this? I speak from experience as I did the exact same thing your pal did. It sounds all too familiar. Now I'm wrenching on a near stocker and am having much more fun but still it is ALOT of WORK and COMMITMENT!

Price: if most of this stuff is mid range- he probably has close to $6-7000 (or more) in my opinion. Used engine and Trans $1000, new ifs $2000, new rad $500, rear disc kit $500, master- $300, frame blasting and paint- $1000, coil overs 200-300. If he's a very close pal he should be willing to tell you what he has into it. I would for my pals.
Any other insights Bolters?

Please do all you homework before pulling the trigger on this one. The shining light of the shiny new truck on a restoration or resto-mod is a lot farther down that tunnel than you think.

This isn't beginner's territory.
Sorry if I sound like a very negative guy, I'm not because projects like this one are done all the time, but know what you're doing.

Last edited by Fox; 06/16/2017 5:08 AM.

1970 Chevrolet C10
Grandpa's -- My first truck -- In progress to shiny
Follow the build in the Project Journal
1950 Chevrolet 1-Ton Dually
"Ole Red Girl"
In the Stovebolt Gallery
More pictures here
1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's
Parts trucks-
1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300