<VV> Which Engine?

[Grant Young]

I am trying to help someone long distance identify the engine that has been transplanted in their 1964 Corvair so I can build him the best set of carbs for it. The problem is that the block and head numbers cross years and are identified differently in the Tech Guide. Hoping there is an easy in-car way to determine what he has? The engine code is TT in front and ZF at the end, which checks as a 62/3 102 or 64 110 in the engine suffix coding chart. I asked him to check the heads to find out which, but they are 3813516. This crosses as a 102 in the annotated cylinder head number list (page 6), but shows as an 84 HP in the more detailed fold out on pages 7 and 8. There is a note (4) that says it is an 84 HP for a Monza PG, assume not same camshaft as 102 HP version.  Guess it could be a hybrid throw-together?
Any help on which to believe?
Thanks
Grant -  the Carb (not the Head) Meister