http://www.slowgt.com/Calc2.htm#Header
Better calculator using bore and stroke.
Stock engine using peak torque:
1.46" primaries @ 42.4"
2.78" collector @ 21.2"
Stock engine using peak hp:
1.62" primaries @ 34"
3.08" collector @ 17"
Still huge! I think for my simple purposes I'll stick with the stocker! Now I don't even know if porting it is worthwhile, since it's at about 1.5" already.