HI I was looking for some advice.
I am building a 60 Size P51 ARF and I am trying to determine the best engine to put in it. To be honest I am really new to the use and tuning of 4strokes but those are my choices for this plane.
A
YS91Z
and a
OS120FS surpass
I want a screamer so am thinking the 120 but is it too big it seems like this would be more for a giant size not a 60 but if it works I think it would be a screamer.

The YS I believe is a something that will work and may be more appropriate but I want to have the unusual. In our field we have several P51 running OS110 and it is night and day compared to the 91 I would like to put the 120 in this plane and add smoke and make this a really nice plane.

The questions are what will I have to watch out for
I know I will probably have to add weight to the tail to make sure the CG is correct but is there anything else.
As I said I am new to the use of 4 strokes so I may easily overlook something basic.

Please let me know your opinions

Thanks