"1) Buy a set of carbide 30 carbine dies for neck sizing" (for loading .308 cases).

Doubt that it would work. .30 Carbine has a pronounced taper and one can't get the .308 neck up into the area of the die where it will be sized. A .32 ACP die may work, but far better to just get a .30 neck sizing only die. It is designed to work with most .30 rifle cartridges, as it does not body size. Neck size dies are made in most calibers. I have them in .22 (I use the same one for both .223 and .220 Swift), .257, 6.5mm, and .30. Of course, one does need a seating die also. The Lee Loader sets (ones you use a hammer with) all neck size only in bottleneck rifle cartridge calibers.