Lump porting is a 30-40 HP gain at most any RPM, so you should do that regardless. 292's can live at high RPM with the right stuff, but like has been stated, the cost of those pieces goes up with the RPM level. Many people try to build these engine based on prior experiences with V8's, and it doesn't work. They have their own unique characteristics that are much different than any SBC or BBC.
