The First Two 336 Models

[AussieO2]

My investigations reveal:-
336 prototype, N34273, c/n 633, F/F February 28, 1961, was
fitted with two x Continental GO-300-C of 175HP.

336 prototype, N........, c/n 636, F/F August .. , 1962, was
fitted with two x Continental IO-360-A of 195HP.

336 production models with c/n 336-001 on, were fitted with
two x Continental IO-360-C/D of 210HP.

Can anybody confirm that this info is correct?

Registration and First Flight exact date required for the second prototype.

Any additional info welcome.