Hello everyone.
Well, it ends with a total replacement of the engine.
The current engine is a Volvo Penta 5.0 GL-B V8 GM, 2 barrel carburetor, 1 electric fuel pump.
Replacement engine, is a Chevrolet Performance 350 / 5.7 V8 Vortec.
The problem is that the camshaft must probably be replaced...