Nitro...No worries on the 46 tank location. Mount your engine inverted, the Saitos and other 4 strokes are ok inverted, most 2 strokes don't like it. The 60 size has the tank too high and it leaks fuel. The 46 is fine. No mods at all. I just put a brand new 82 in mine. I had bench run it for 40 minutes and installed it. No leaks, perfect, very slow idle, great transition, great power. No problems. I use 30% fuel...you should also. The Saitos love it. They'll work on less, (gjeffers) but at least at my elevation the 30% is clearly better.

Thanks
Barry