Ball milling reamer??

[cuisinartvette]

Only thing I dont care for with EH is you cant control where and how much material is removed, (everything is just going to be "bigger") and in my hackster opinion thats real crucial to how that motor is going to want to act.
I call it lazy mans porting but to each his own.

[A26B]

There's another element to porting that should also be considered, which is proper port location. Unless you want to be hand cutting new gaskets, the ports should be centered to OEM dimensions at the interfaces when they are ported, either by a template or machine boring to correct specs. Extrude honing just goes wherever the port(s) are originally, core shift & all.

I agree completely with Locobob's comments about core shift being prevalent and also his doweling for alignment. On the 405hp engines, GM installed alignment sleeves on the outer inj hsng/head bolt positions to establish positive alignment. Marc Haibeck installs the dowel sleeves on the 375 hp engines when he ports. Putting dowels on the plenum/inj hsng is just as important.

Even still, unless the port work is aligned dimensionally correct, it's a toss-up even when you buy gaskets for ported engines , whether they will not overlap the port somewhere and require trimming. Not a big deal but just something that will have to be done every time you change out plenum gaskets.