Fooseball, if you don't flip it over to start, residual oil will be trapped in the crankcase rather than being drained from a side/down muffler. You will get some floods. You can well get floods when you flip it over as you will have fuel running into your muffler while starting. It's gonna be messy to say the best.

Now as I see that picture of an engine mount simply extending into a notch in the firewall, well good buddy, you better get some extra fingers or a hand because one day that engine, will come right out of the front of the machine when you are starting it. Like the firewalls in a number of ARFs, that ain't worth a SHOT! I have seen too many front ends come off models and I heve seen a guy lose most of his right hand when the firewall came off during a restart after a rather hard landing.

If you don't cut that machine apart, and rebuild the front-end, all I can say is "Best of Luck and you were warned."