Porting an engine with a drill will destroy it.

Plain and simple.  No ifs, ands or buts.  I have a die grinder, but nothing more than a pancake compressor so actually using it is painful.  I could buy a larger compressor, but then I have to find someplace to store it.  Having everything else I need to start the porting process, I improvised.  Chucked the parabolic bit into my drill and had at it.

4 hours, and only one oopsie, later, I had a nicely ported intake, and a drill with a chuck that wobbles like a drunken sailor.  I'm talking at least 1/2" of play at the tip of the chuck.  Fortunately, these drills are cheap at Northern Tool.  I can get them for $15 when they're on sale.  The extra handle gives you a lot to hold onto as you're grinding away; hence, the single oopsie.  You hate for tools to be considered disposable, but in this case it worked out really well.

http://ernest.isa-geek.org/Delta/Pictures/ EnginePortingTemplate.jpg
http://ernest.isa-geek.org/Delta/Pictures/EnginePortingIntermediateHousingRear.jpg  http://ernest.isa-geek.org/Delta/Pictures/EnginePortingRearHousing.jpg
http://ernest.isa-geek.org/Delta/Pictures/EnginePortingIntermediateHousingFront.jpg  http://ernest.isa-geek.org/Delta/Pictures/EnginePortingRearHousing2.jpg        http://ernest.isa-geek.org/Delta/Pictures/EnginePortingFrontHousingOopsie.jpg <http://ernest.isa-geek.org/Delta/Pictures/EnginePortingFrontHousingOopsie.jpg>