Believe the Rocket V-8 from Olds was cast iron. The engine in the Buick was all aluminium alloy and as was pointed out the problems were with corrosion (don't think the Yank mechanics were too up on how to deal with the cooling needs either), wear and overheating. Along with some disimilar metal corrosion.
Believe one of the fixes for wear and possibly heat transmission thermal distortion problems was iron sleeves in the cylinders.
Buick does (or did) a lot of the engine development for General Motors in the US (Chevrolet, Cadillac, Pontiac, Buick and Oldsmobile) and builds the high performance engines (like for Corvettes). GM and Chrysler (or Daimler Chrysler or whatever they are today) are two different animals. GM did own Opel and some other stuff in Europe and of course Holden in Oz.
IF one were going to do a liquid cooled engine for an aircraft application a light alloy block would be a reasonable start. Believe a turbocharger to get max power out of smallest engine would be needed and a really healthy cooling system.