The answer is simple, the car should be in conformity with the Homologation paper 127, even if it was built before that date. The FIA does not seem to be worried about "anteriority" (perhaps it should?) as long as the car was built in Period F (pre-31/12/65).
[I have also wondered whether the racing driver should also be born before this date
].
The main problems seem to be elsewhere. The original homologation gifts the standard Elan with a racing specification. Many manufacturers used the same trick.
But not all of the "racing spec" makes it into homologation pre 31/12/65 (despite the document being published by the FIA...). Is the homologation paper the basis for the vehicle or is it the "racing spec" annexed by the FIA ? I see the latter as a clarification of the former.
In the 1990s, the 26R was in the "GTP" category and the racing Elan in the GTS10 category. Why...and how did
the "26R" then join GTS category (did the FIA outlaw production GTPs ?)...And why some retailers identify both a 26R and GTS specification for certain parts, adding to the confusion of "anoraks" like myself.
The FIA also seems to overlook that there were also two types of racing Elan bodies and two chassis. The S1 version (with both pop-up and perspex lamps depending on the market) and the S1 1/2 / S2 with the egg-shaped (or "Chinese") front lamps (not for US) and a high back chassis).
I'm also unsure as to the exact chronology of "26R" wheels: they do not appear to be those used in period (no gaps between the main spokes), but the FIA seems to have blessed what might well be a post 31/12/65 version...
My personal and possibly wrong conclusion is to go for the Racing spec that applied to the period of my car (early 1965) and this points to the S2 racing body and high back chassis. I will also use Minilites as the original type wheels are made...