Hey vskiwi,
Why don't you pop down to your local model shop and talk to the proprieters! Palmy is only a stones throw from Feilding.
I hear they used to both fly pattern "back in the day" and I would guess are a wealth of knowledge
I'm sure they would agree with jas's comments re MK mechanicals versus Springair, sources for stuff etc really helpful couple of guys and really know their stuff!
Good luck with the build, who ever advised you to buy that kit knew what they were talking about