[Matra et Alpine]

Well I do know there was an evolution to 1432ish for the engine in later competitions but neve homologated.
As you pointed out there is differing info. The AUDISPORT yearbook ( the bible of rallying ) lists the final Turbos as 1430 BUT in the specs for the Maxi it lists 1527
Hmm, perhaps thre were some issues with the homologation numbers ? If they didnt' make 200 of those then they woudln't have competed unless they were de-sized to the 1397. THAT might be one explanation - the engine was made bigger and then reduced again for championship points. Don't know as we now have 4 sources all different and ALL reputable
I've asked the R5 experts in the Alpine club. Some of these guys copmeted in them and still do on the classics, so I'm expecting a definitive answer from them.
Given that Renault are French I woudln't put it past there to be a little cheating or bending of the rules causing the confusion As there is ONE Q re the book you cited -- the "Tour de Corse" model was already built to compete and was homologated to run against the GroupB NOT Group4 cars .

EDIT: Reading the finer engine details in the Audi book - The MAXI engine is 77/82 and the 'standard' was 76/77. So that would suggest thre WAS a new engine of about 1430 using the same crank as the earlier 1397 and THEN the engien was stroked to get 1527. Quite possibly there are variants with the mix of crankshafts and everyone is right and that there ARE 1397, 1430 and 1527 examples of the MAXI out there

I'll take the definitive answer when some of the French members of Club Alpine respond to me query. One of them is liekly to even give us engine numbers fomr his car to prove it