How warm did you get engine .ive seen one that blew oil out when cold but once was hot ran ok, still used a wee bit of oil but nothing too much . how much oil are you losing anyway . i've a friend who got pistons and liners ex sweden and rebuilt his abbot without to much hassle
I had similar problem ,turned out to be a generator which had seized and prevented engine fro turning ,best to check with either large adjustable or a 55mm socket.either problem will require pack out