ScobraC:
IMHO if you are going to go the BB route, then you would like to have tons of power and especially torque to make up for the extra weight. 425 HP and similar torque numbers will pale as time goes by. Build it right the first time and shoot for over 500 HP.
427 will provide the foundation to support higher HP numbers (not to say it can't be done w/ 428).
Oil passages are larger diameter on center-oilers and SOs. Cross-bolted mains for sustained high RPM use in case that's what you intended.
I am building a TunnelPort.
Bill