Tech when You and I were younger there were all Kinds of Job's to be had and we could make as much Money as we could stay awake . But Today that's not the case . Yes no way around it a Roller Camshaft and Rockers are the Better Build . But a Flat Tappet Camshaft Engine can be built and run an easy 100K + Trouble Free Miles . I built a Few Last Summer . My Truck Runs one of them Engines every day From High 90's to -10 Deg Weather . And that was not a High Dollar Camshaft . That Engine run excellent .

Yes with 170K Miles your Engine might have so much wear in the cylinders that it will need to be Bored more then 030 . Might be better off to use it for a core trade in on a Built Short Block . Maybe some one has a Reman OEM one piece Roller Block you can Trade it in on .

For a truck like that a 3.55 Gear would be good 2500 Stall Speed . You could Build a High Torque 355 with a Set of High Flow after market 2.02 1.60 Vortec Heads And a Camshaft Max 480" Lift use a Weiand Stealth Non-Air Gap Vortec intake with a 750 Performer Carb 1 5/8" Long Tube Heads .