You're going to bush the chambers, I guess. The liners, once chambered are going to be mighty thin - about .060" wall over the case head. On top of that, they're going to be way undersize in the .12 bore chamber. I think I'd use 7/8" liners and turn them down - perhaps swamped through the 2/3's section to reduce weight. At .875", they'd be able to be fitted properly to the 12 bore chambers at least.
; .625" would fit a 20 bore almost correctly, except again for the chamber. I don't think .625" is large enough for a .45/70. They would fit for lining a .20 bore muzzleloading barrel with little turning.
: The barrel wall is quite thin as it is, only 83 1/2 thou. per side from the outside of thetube to the bottom of the grooves. 1/10", or 100 thou. is deemed to be only useable in shotguns or large smoothbores at the breech with 3 dram loads - developing only about 6,000LUP. Round ball rifle barrels producing 14,000LUP or a tich more are usually closeer to 2/10" thick on each side. Pretty thin - perhaps I'm overly cautious - be about the first time for that. Even light .45/70 loads produce 24,000PSI to 28,000PSI. CUP and PSI are virtually identical numbers in a .45/70.