Usually pi options are Sea Rocks with smooth portions, like a certain Rhodesian you and I discussed. All I can figure on this one is that Coppo wanted some extra money. It does indeed look like it has the pi stamp.
An Italian shop has a carved pipe up now, fresh from the factory, stamped Old Antiquari. They. Are pricing it as a Sea Rock, and say in the text that it is a mistake. They say "Mr Coppo does not often make mistakes" or words to that effect.
American collectors put too much emphasis on claims made on the basis of nomenclature where Castello's are concerned. There is an Old Antiquari on eBay now, or recently ended, that has no size stamping. The seller claims it must be really old because it is "pre k grading". No such thing. There is simply no room on the nomenclature panel. Nice pipe, BTW, just not worth an age premium. I think I know who the seller is, and I would have thought he would have known better. The style of the blast could not have been produced by Coppo until he got new equipment around the mid 90's.
Castello has changed the definition of Pi in the past few years. Now a Pi can be a Collection. They rusticate the shank or bowl and leave a piece smooth and call it a Collection, and leave the Pi stamp off.
I've never been tempted by a Pi so I don't know the price range for them, but I always assumed it was somewhere between Sea Rock and Trademark. Seeing partially-rusticated Collections kind of makes me throw my hands up.