Somewhere between 20-30 hours I'd wager. It was on-again/off-again so I can't say for sure. Between them and other projects it dragged out over the course of a month.

The first 50% of the first head I ported was slow as heck - then I got a set of carbide burrs at Sears. The burrs knock down the big stuff so much faster (and more accurately) than a stone or cartridge roll.

I almost bought a set of used World Jr heads for $400. With the valves and all I've got about that much in these. And I did it myself. They'll be great in my old Bronco.