Bore and Stroke are determined by what size engine you want to run. Chamber size is one of the critical numbers in determining the Compression Ratio. Valve size and runner size I just go with what I know worked good for the street. Had it been an all out race engine then I would have used a 2.06" intake and a 200 or 210 runner. Experience and listening to the guys and companies that build racing engine is where a lot of this information comes from.