Rolling coal is stupid.
Edit: But hood stacks are awesome, so I guess you break even
For more power get your timing fixed(check the chain stretch, get a new tensioner spring, and drip time the IP position)
Adjust valves("free")
check your overflow spring, or replace it ($30)
get your injectors rebuilt with 315 nozzles($150? 200?)
turn up the boost just a little until it doesn't smoke at full speed
get a pyrometer($75)
then we can talk about more mods
The 617 is definitely a high revver for diesels, the governor is set at what, 5500rpm?