Arizona Fusilier, since you've sold your rifle I guess it hardly matters now, but the Vanguard in .223 used to have a 1-12 twist. They began using a 1-9 twist a couple of years ago, I think around 2013.
1-12 I think will be on the bubble with the 62 FMJBT, about all one can do is try it as others have suggested.
Agree with Fusilier, 1-7 or 1-8 gives the broadest range of choices, personally I like 1-8.