Shonky,
I bought a '58 Series II a while ago as a spares car, it had a 2.25 fitted but came with the original 2 litre motor as well. The idea was to use the 2 litre motor as a spare for my Series I.
I'm now looking at restoring the SII (at some point in the future) and putting the original motor back in because it is rare to find them with the 2 litre fitted.
The 2 litre was only fitted to the early 88" SII's, as Diana said probably just to use up existing stocks. The long wheelbase was launched with the 2.25 motor.
Series Two Club
Colin