Good point, Mech. Most modern V8s have 5 main bearings. The center 3 bearings are under the most stress, so they got the 4 bolt option.
I think most stock 4 bolt blocks had all 4 bolts going directly down through the cap into the block. Some blocks had "splayed" 4 bolt mains, where the outer two bolts were angled outward into the block. I don't know which provides more strength and stability for the bearing.
There are other bottom-end reinforcement methods for engines, such as using ARP studs instead of bolts in the mains, or using a block girdle that links all the main bearing caps together. Of course the wilder you get, the more it costs.
But the short answer is that a 2 bolt block with new bolts, new rods and a balanced rotating assy will make a bunch of power and live a long time in a street/strip application. But the block is only the starting point. Using well matched, quality parts throughout the engine is the key to success.
good luck
chip
