I don't have an Ampco but ran a Marvel Oiler on my Judson set-up for 10 years. The Ampco works in a similar way to the Marvel Oiler and both use Marvel Mystery Oil.
If the question is "do they work" the answer is yes. Top end cylinder lubrication is a very old concept and since the elimination of lead in petrol there are many who believe vintage valve train doesn't get lubrication it needs.
If you're worried about that then an oiler that supplies an intavenus drip to the top end will keep you happy.