359 Barn Find

I found a 78 359 big cam/13 speed for $6,000. Needs interior, glass, 5th wheel plate, and tires. Owner has all glass and new weather stripping and lights that come with truck. Hasn’t been started in 3 years.
Limb fell on truck and broke the windshield so owner bought all new glass had the truck painted, put new rear drums and shoes on it then drove it home with no windshield and parked it. 3 years later there she is. He’s a diesel mechanic intended on fixing it and selling.
My goal would be to get her road worthy and start working an end dump I have.
I’m not too knowledgeable on these older Pete’s, I have a fertilizer business and haul all my own material. I’ve always wanted a 359 but I was just curious about what I’m getting into with this set up. Thanks in advance guys, I know it’s hard to comment without seeing the truck but just hoping to spark some discussion with the fellas that know more than me.

 

Everything looks solid even the air bags aren’t dry rotted. Just kinda looks like an intimidating project because the glass is all gone and the interior is toast. Plus the guy had it painted flat black and it’s sitting in between a bunch of junk.
What’s the scoop on the 13 speed? Reliability is my only concern. I have only ran trucks with 10 speed eatons and a international with a 9.
I will only be hauling 25 ton loads of fertilizer.
Oh the dash says 279,000 so let’s go ahead and assume that’s 1.2 million on the ol girl.

 

I know questions like these are a can of worms. And I know nobody could possibly be specific in a response without seeing the truck, way too many variables.
I’m just looking for tips on what to look for when I go inspect again.
Parts might be hard to find/expensive/unique to this truck?
Long time reader first time poster on here.
Appreciate you guys again in advance.

 

Yep, not well covered. I’m going to take some batteries over there and fire it up. If none of the gauges work I’m going to video call you guys and just have you walk me through re wiring the dash. Just kidding.
Local Cummins shop today said around 10k is average rebuild cost same place told me an N14 wasn’t worth rebuilding because it had heat cracked pistons though. Put a new head gasket in and it’s been running for 2 years haha.
I’ll try to get some pictures for you fellas
Thanks