If you acquired the firearm BEFORE you had an FFL, disposition does not need to be recorded...even though it might be a "collectible" firearm, it need be treated no differently than any other since it was purchased before you were licensed.
Where'd you get that idea? The law seems to disagree with you.
18 U.S.C 923(g):
(2) Each licensed collector shall maintain in a
bound volume the nature of which the Attorney
General may by regulations prescribe, records of
the receipt, sale, or other disposition of fire-
Any time you acquire or dispose of a C&R firearm while you have a C&R license, it needs to go in your book.