Krproton,
Sounds wonderfull!!
It is very nice to have an ARF that if you use the manual as the bible for selection of engines, and it balances as it states
with no added weight!!!!
This sounds like it is a great plane, that I will be sure to look into for the future!
As far as engines, I can always get dif onces..... No problem there!!
I have already found homes for 2-of the 3 .91's that I have anyway!
And yes,
I really do understand what you mean when you would have to make all these adjustments to the fitting of many parts, if you did not use the recomended engines!!

The YS 63 are wonderfull engines, my only concern would be that of the length of the engine..[X(]
They make stick out too far because they have a very very short crank shaft on them!
You may have the engines clylinder hanging out of the plane....

Justin