The original spitfire fuselage is 62cm. Zeeko now have a 65cm Double Agent fuselage. The Double Agent name seems to originate from a 75cm Amplifier fuselage which could mount the mast in a more rearward position for windfoiling. The 65cm fuselage doesn't have the option of two mast positions on the fuselage.
The Amplifier mast/fuselage connection is a stronger way to connect the fuselage to the mast for wider/larger wings. It is also symmetrical, so the fuselage can be mounted either way. Zeeko owners of the 65cm fuselage would just need to buy 2 of the new Spitfire wings. I don't know if the 75cm fuselage would work with the new Spitfire wings.
This should mean that the Spitfire could use the carbon mast and new wings - with the angle of the front wing being adjustable. The larger wing also has the middle of the 3 off M8 bolts offset for more rigidity to the fuselage. I think the angle of the smaller wing relative to the larger wing on the Spitfire is very precise though, so it may not suit altering the pitch of the smaller wing.
The original Spitfire front wings might be able to be used on the Amplifier fuselage with suitable spacers - because the inline bolt pitch is also included on the Double Agent fuselages but the old front wing wouldn't fit because the new fuselage uses M8 bolts. The Spitfire fuselage uses M6 bolts for the wings.