[madmaxx]

what the difference in weight and cost with an aluminium block vs cast iron? it would seam the cast iron is a little more "idiot" proof as you dont have the thermal expansion concerns as compared to cast iron. My preferences are;

Engine designed for longevity (100K). preferable roller cam which does not require adjustments and low spring pressure as the valve train is the most demanding service in an engine.
Massive low end torque - release clutch and engine doesnt stumble
If possilbe 12 mpg.