I've been waiting for this thread..
Blowdown is degrees of rotation from when the exhaust port opens to when the transfers open, it's still in play.
He is tuning that engine to a specific cylinder (the DR 43mm). When I cut my first crank (standard duration Top, before anticipado ones were available) I cut it to the specs in the cylinder kit (Malossi) instructions. I don't remember the exact numbers it resulted in, mainly just checked they were in the ballpark and that it shut before the transfers opened and vice versa, learning how it worked. Now that I snapped that one I'm going to rebuild using the marzuchelli anticipado. I haven't compared them Yet but hopefully I won't have to make much of an adjustment.
You've probably already seen this, but there's more info and numbers here: