Knowing full well how much time you have spent working on them I would like to be able to tell you to go ahead and shoot them, but even though .38-55 operates at much lower pressure than 7TCU, in all honesty I would not do it myself and cannot in good conscience tell you they are safe to shoot. I have been taught that they are not and have seen the results of blown cases. (Once, a dead rifle and a shooter with pieces of it embedded in face and hand.) Even if just the case blows without damaging the gun, a faceful of propellant gases leaves you looking like you are trying out for a part in The Jolson Story. Having once been severely burned, I wouldn't wish it on anyone, ever. When it's Wile E. Coyote it's amusing, but when you are in the emergency room there's nothing funny about being crisped.
But, the cases may be salvageable as .30 or .357 Herrett's - the weakened portion of the case neck/shoulder would be cut off when they are shortened.