The OAL thing is taken way too seriously. All that matters is a) if they will fit in the magazine (of a mabazine gun) and b) if they will fit in the chamber. I'm guessing your big thumper might likely be a single shot; if so forget about the first one. As to fitting your chamber (I'm guessing you don't have a Stoney Point gauge), start with the bullet seated way out. Slip it in the chamber. It probably won't go because the bullet hits the rifling. Now, take and incrementally seat the bullet about .025 or so deeper and try again, doing this till the cartridge goes in the chamber. This is without significant force, but don't be afraid to assist it a little. Once it fits, it is probably best to seat it about another .020, then go shooting! You're home. If it is a magazine gun, then when you get to this point, see if they'll fit the magazine. If they do, you're in. If not, you have to shorten them some more until they do--or shoot it single shot. The max OAL for your gun, with any specific bullet, is one of the above two, not necessarily what any book says. Max OAL in your gun might be longer or shorter than someone elses. That is immaterial, unless you want to shoot the shells in both guns, then, obviously, you'ld have to go with the shortest one, which, incidently, won't hurt in the longer gun at all.
Oh, by the way, you're probably going to be crimping these loads, but obviously, don't set your die to crimp until you find the length you need.