New parts new aluminium piston from ex model engines

Its wy the post on laping tool m'y old Venom need new piston so tink of use one old cylinder tapered and use it To fit aloypiston in wit laping tool then try fit in m'y Venom dont want laping compound in m'y Venom cylinder so it can use both piston is just To try is sur Not the best way just curieux of the résultat wit aluminium piston?