The mounting angle problems vary from engine type s. For the most part YS 4 stroke/cycle engines will run very well in any position. Many engines will not run reliably when installed inverted. If the exhaust port is at the lowest point of the installation ,flooding during starting is a lot less likely. This is true with 4 strokes and 2 strokes -GENERALLY.
All in all you can feel confident when mounting the YS in any position. Good Luck, LF