Time for an orientation check... My impression is that Dynaflite used to make a .30 size Mustang (a while ago) and a .60 size mustang (fairly recently). Now a 51" warbird for .60 sounds unlikely to me, so I gotta ask... are you putting a ball bearing, schnuerle ported .46 on a vintage .30 size plane?

If so, I'd expect you'll want at least as much torque as a standard servo (although the CS-12 does deliver about 80%). I'd go with something bigger, if it'll fit. If a more powerful servo won't fit, I'd get a bigger airplane -- seriously.