The less you operate the engine until it gets fixed, the better.
1994 was the transition year for the IP. and went to a 5521 pump.
You should be able to just swap the IP over with info you posted.
Harland Sharp makes upgraded rocker assemblies for the 6.5L but is pricey at $600.
You can view them on the Leroy Diesel website
1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
2/0 Battery Cable Upgrade - PT Wiring Solutions
PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
4.10 gear ratio
OptiLube Winter Formula
Proud member #1039 of The 3500 Dually Club