In my opinion, the 2 or 4 bolt controversy hinges on several things. The weight of parts in the reciprocating assembly, the rpm's and the power being made. You might be able to spin a 283 to 7,500 or even higher with no problem on 2-bolt mains, but trying the same thing with a 383 might end in disaster if using off the shelf parts. With super light parts, you could probably do it time and again. You might bolt a 4-71 onto a 283 and blow it up at 5,500 because power exceeded the design of the webbing in the block. I'm talking in a relative manner here, so take it with a grain of salt.