Fellow R/Cer's

I just purchased an Kangke Extra -60 and I want to ask what is the best engine I can power it with. There are other threads about this but no one specifies 2 stroke or 4 stroke power. Everyone just gave numbers of my 120, my 91, or my 100. Which one? I'm considering a Magnum .91 or 1.08 2 stroke. Price is also a concern as 4 strokes get expensive. I would like to be able to have unlimited vertical.....that's what I'm after...along with everything else. Magnum claims the .91 and the 1.08 both weigh 23.7 oz, but the 1.08 has a tad bit more power....is it worth the extra $10 between the two? And will I have to modify the engine mount to get a 1.08 to fit? I don't ask for much, I know. Thanks for any input in advance.

B.T.W. I current own the GP Extra 300 .40 ARF, and just one look in the box and a world of difference in the qualily & true-to-scale lines... should have gotten the Kangke .40 as well. No disrespect to GP, I love that plane, but Kangke's on the money!!