450/400, which they've already done.
A 375 H&H Flanged would be nice, also, I agree. I had one in 375 H&H belted. It was a sweet rifle and I never should've let her go. But, I'll have another, some day.
Regarding barrel length, Ruger routinely placed 26" long barrels on the magnum rifles (7mm Rem Mag, 300 Win Mag, 338 Win mag, etc.), but 22" on most standard calibers (270 Win, 30-06, etc.), and 24" on the Tropical.
And yes, every rifle deserves a proper set of sights! As I'm getting older I'm finding it more difficult to shoot well with irons but they're still all I use. I figure that if some guy can get within 30 yards and stick an arrow in an animal, I should damn well be able to function fine with iron sights!