Magnum heads on LA block H.p increase

If memory serves me correctly the pre-magnum roller lifters have the oiling hole but better double check. And I would personally run a roller cam short snout for a magnum is ok if you run a electric fuel pump or get the adapter for mechanical fuel pump.

I don't remember the 1/8 mile times on the 5.9 magnum. Locomotion a member here I believe was running into the upper 12's in the 1/4 with the 300hp 5.9 crate engine. And the 300hp crate engine was a factory stock 5.9 truck engine with a long snout cam for fuel pump but same specs as production truck engine.

The 380hp was a completely stock 5.9 they pulled off of the assembly line and changed the cam and valve springs. And ran a light weight A-body into the mid to high 11's in the 1/4

Those 2 engines were dyno tested at those hp levels by the factory with 600 or 650cfm carbs. Add a 750cfm carb and the 380 jumped over 400hp and the 300 I belive went to 320. Somewhere in that ballpark anyway