I have several of these planes and I've done both inverted and side mount engine installs on them.

If you use a Pitts style muffler a side mount is the easiest way of dealing with the engine.

I like the inverted mount for looks ( since you don't see the cylinder head/glow plug cutouts this way ), but mounting the muffler is more difficult if you are using the stock muffler.

With an inverted mount I had to put on a muffler extension to bring the muffler out far enough to clear the cowl.

Putting the cowl on and off is also more problematic with the inverted engine, as I have to remove the muffler to get the cowl off.

Then the muffler screws are inside the cowl so getting at them is not easy, although I have two access holes to remove them.

I'd suggest the side mount to you with a Pitts Style muffler for ease of setup. Also removing the cowl will be MUCH easier.