My next project will probably be some kind of scale aerobatic plane, and I am thinking of building a GP .60 Extra 300 and putting a four stroke engine in it.

In most of my planes I haven't been able to place the tank at the correct height relative to the needle valve. I can't say that I have had problems, but it leans out a bit from full to empty. Normally I set the needles with the tank nearly empty, slightly rich from peak.

Is tank height a problem in the GP .60 Extra 300?

Should I buy a pumped engine? Or a "normal" engine and a Cline regulator? Or is it OK without any pump/regulator?

If I buy an OS, is a 91 enough for non-3D flying, or should I get a 120? I'm not looking for unlimited vertical, but it must have enough power to fly the plane with authority.

Is there any difference in sound between the different brands of engines? My friend has a Saito in his Goldberg Cub that sounds fantastic, but it is the only four stroke I have heard that is larger than my OS 52. Does the good sound come with size, or do Saitos sound "better" than OS? Because nitro is expensive here, I'm not too happy about a Saito (I've heard that they like 15%+). I have had good experience with both OS and ASP (Magnum/SC), so it'll most likely be one of those.

Any comments/advice appreciated