they are pretty much unkillable.
Make sure you only do Beru glo plugs. The other brands have a reputation for mushrooming and breaking off. Then you have to pull the head to retrieve them.
I'd just go ahead and plan on ordering all of the return line fittings as well. There's a good chance it has air intrusion that also leads to extended crank times.
and make sure you run some kind of fuel additive to lubricate the DB2. Since ULSD happened the lubricity of fuel is way lower than what the pump was designed for. I started with diesel power, but ended up just running 2 stroke oil in the fuel after a while. Way cheaper, but I was also filling a 50 gallon tank in a truck that got 8-10 MPG.