I'm putting a 6bt in my 87 F350 crew cab and am wondering if it would be better to buy a running motor or build one from the block up?

 

Depends what you want. Simple move-around, like a plain-Jane farm truck, or hot-rod? If just want it to run/drive, get a running one and plop it in there, and call it a day. If want a hot-rod, better to build it yourself prior to the install.

If you do the plain-Jane plop-n-go, you can still punch up some more HP/TQ for better drivability later on, if you like, but, it'd pretty much be limited to stuff that's external to the block. (turbo/injection upgrades)

 

I'm new to building diesels and I really not sure as to what internals I can do

 

Is the F250 "unemployed" or do you need it back on the road pretty quickly? If you need it prompt, use a running engine. Block-up builds take a while, because you've got a WORLD of variables to address, such as what cam, what pistons, (the aftermarket has gotten pretty big for the "B") Or, get a second block and do the build at your leisure. If you've built a gas engine before, all the rules are the same, but, the specs are tighter for a Diesel, and they're less forgiving if you're a slob. They're more forgiving with nasty road conditions, and nasty operating conditions, but, they have to be built right.

 

No it's not employed it's just a DD I have built a few gassers in the past I just don't know where to even start looking for internal parts. I just want to be pushing some where around 350-400hp. I'm going with POD injectors 3200 governor spring, fuel pin and ARP head bolts. I have no turbo in mind and a custom inter cooler

 

For that power level, you don't need to do a full-block build, so long as you get a runner that passes a compression test, and doesn't appear to have ever been damaged. Get a "buddy" in your geographic area to help with evaluations of candidate donor trucks.