I am not a good poster but some of you have probably seen my posts on other D-50 / Ram-50 sites.
Anyway, I've been building / tearing down these trucks for MANY years. . . .
I am NOT an expert, but have been able to provide historical information / parts to other forum members in need.
My love affair w/ the Mitsu 2.6L, don't EVEN ask me what that is about. . . . . .

Bottom end:
So, I got a 2.6L Turbo block, bored it 0.100" over, (3.69"), built a stroker crank, (4.11" stroke).
This equates to 2.88L or in industry terms, 2.9L.
The turbo block includes the piston coolers, very helpful since I have stepped domed Venolia forged pistons. 10.9:1 static compression. 220psi per cylinder, yet running 89 octane w/ the piston coolers.

Top end:
Marnal head, (Spanish built 2V head), (some of you might remember the group buy I did, about 10 years ago).
Manley valves: 48mm intake, (w/OS valve seats) / 38.5 exhaust valves.
Ported intake, exhaust polished.
Mitsubishi 3.0L V6 rockers, 1.6:1 ratio, hrdraulic rollers.
RPW, (Australia), roller cam/ .530" lift / .295 Dur. + Head Gasket @ 0.100" OB, ($1,000.00 FREAKING US DOLLARS !!!!!)

Ignition:
Kill the stock distributor!!!!!
Electromotive dual coil-pack
More to come . . . . . .