Ball milling reamer??

[Paul Workman]

OK, you machinists out there...Where would be a good starting place to start looking for a ball shaped milling reamer that is either chased or pulled thru a curved (i.e. intake plenum and IH) (aluminum) runner? Aside from a drill press and assorted air-driven tools, I don't have anything in the way of machining tooling. And, wanting to open up the plenum runners, I'm looking for a tool that a lay person could push or pull thru the runners that would open up the 33mm runners to a 36mm ID, perhaps in stages, if necessary. Sound crazy?

I've done more than a "little" time on a die grinder in my dayz, but looking at the LT5 runners makes me think there must be a better way than a TC ball bit and air-driven die grinder...NO?

I'm thinking of a TC ball cutter that can be attached to a flexible joint so the tool will (more or less) faithfully follow the existing centerline of the runner while opening it up.

Am I making sense, or am I doomed to hours with a grinder?

Also, where would one find a 36mm ball gauge?

TIA,

P.