For those who have done porting on the cast iron end housings; what bits/stones/burrs did you use to open up the intake ports?  Does it take several types?  Which for rough cuts; which for polishing up? I'm ready to work on my 20B, and want to do a mild street port on the intakes.  I have a 'dremel' hi-speed tool, but my bit selection is down to 1 or 2 left.  What to buy??
Phil in IL  RV-10 in process