sounds pretty good but I'd maybe go a tad smaller on the cam/carb & you could find what 383 deck heights come in at which'll b diff I'm sure from the listed height & with the piston CH/rod C to C & 1/2 the stroke & the head gasket figure your CR as close as you can on the KB calculator. Are the KB 400's a quench pad piston and b aware that the quench pad height is not included in the CH dimention & iirc the ones for my 451 (dont remem the # right off hand) the pad is an addt'l ~.060". You'll want the SCR up higher & I'd consider having someone good, port em as you've went this far otherwise (reportedly) you may b dissapointed (if no porting) & will b leaving ALOT on the table. Sure I cant persuade you to build a 451 (400 B block/440 crank) . There'd b less down time as you'd b driving the 383 till the 451 is ready to drop in & the outside dimentions would b the same so all the externals would fit right up & the torque diff would b night and day