I [HAD] 333 @ the wheels at 13lbs on an old engine (90k when seal left)
I have T04S, GReddy SMIC, 1300cc sec. inj., RP fuel pump, full ignition (jacobs box, coil, wires) straight exhaust, PowerFC, HKS intake. I am sticking in a street ported engine w/ a GReddy frontmount and also a Koyo radiatior for the cooling. I talked to jason and I was told about a guy w/ 470 at the wheels.
Id go single if you have the resouces for it. If you put on the big parts now and add in the little nick nacks later Id do it. I think I have somewhere around 10g's under the hood. Also remember when you get your engine rebuild try and get it balanced so your redline will go up. (Nothing feels better than not having to shift untill your next gear is already well into the powerband!)