There isn't a great deal of difference between a .63 and .58. How much material can be removed from the .62, to make the .58's liner thicker? If too thin, it might not remain perfectly smooth inside, due to obturation with pressure on firing.
I'd think it would be safer to line with a .54 smooth liner, but that might make for quite a heavy gun.
B. Hoyte would indeed be the best person to ask.