http://www.sigmfg.com/cgi-bin/dpsmar...FV4.html?E+Sig
i think it would fit fine, maybe a little cutting would be all that is needed. is the plane already built or are you building it??? if your building it then i wouldnt worry about it, if its built than it may be a little harder. the only problem is going to be nose weight, this engine weights 5oz more than a .35 sized engine so you will need to put the battery in the back of the plane. with that engine the plane will haul a.. use a 9x8-10 prop.

what are you trying to accomplish? a plane that really moves or a floater that has some speed? with the .35fp the plane will float better, but if your looking for speed then shove the magnum into it.
worse case senario, you take that magnum.40 gpa off of what ever plane its on and put it on the sig (weights much less than the magnum.46). then put the new magnum in its place. that will give you a more plwer than the 35 with not much weight gain.