So I was looking into buying a fulcrum and a lost grey lightsaber. The only questions I have about the blade is if it's possible to change the hilt width and if when customizing the lightsabers should I get a 32" for the fulcrum and a 24" for the lost grey. Those sizes would be for dual wielding and also because Ahsoka has one shorter blade for fighting.
Or does the hilt length differ in the blades meaning I don't have to change the blade size?
The Fulcrum is more or less the "bigger sibling" to the Lost Grey. Sidious Sabers does a nice comparison of both on his YouTube channel, but long story short, the Fulcrum's hilt is a little wider (at least part of it is) and it is indeed longer than the Lost Grey. There's no changing the size of the hilts. I'd check that video out first, seriously; you might have a little difficulty with dual wielding given their size. The Lost Grey isn't exactly a small hilt itself.