**600hp sbm block limit? Or is it bs!!**

I am in the process of planning my factory 340 block to withstand 600-625 HP...
-Forged MOLNAR crank and H-beam rods .
-Diamond pistons ( lightweight )...
- ARP studs
- Internally balanced .

THe ONLY thing i am not sure of and was hoping somebody would of brought it up is one if these 3 below for mains .
1. 2 bolt billet mains
2. 4 bolt billet mains with splayed outer bolts.
3. 2 bolt Billet aluminum mains ...

My first choice would be aluminum mains due to helping in diverting harmonics away from webbing ? Apparently there is no life span like aluminum rods have ??? Any suggestions ?