Those blocks had the material for real 4-bolt caps and very thick bores as compared to any factory block. The limitation at that point becomes the ability to actually make the horsepower levels that would stress the block to breakage. There simply are not heads good enough to make a lot more horsepower on a 59° block. Ask yourself why the stroker LA and magnum based engines are all pretty much stuck between 600-700hp regardless of the head package or camshaft. You can get more going with special pistons, ring packages, compression, dry sumps, etc. but it really takes the 48° block and head packages to get beyond that airflow ceiling.