Here is an alternative engine option that we have done to my 1950 P19 fastback - a new " block up" rebuild of a Chevrolet 4.3 vortec V-6 engine with a 5 speed transmission. The fit in the engine compartment is just right with the drivers side exhaust manifold re-configured upside down so exhaust pipe goes forward then down in front of the fan before going back under motor to the rear, thereby missing the steering box. Motor was rebuilt from a 1988 S10 so is carbuerated without all the electronics except for electric fuel pump. The setup runs like a champ.
True, I have zombie mopar, but the fastback styling of the P19 is one of the coolest hot-rods out there!!
Zorba