Just thought I'd add a few things from my build of the Raidentech yellow Long EZ model over the past few days.

With regard to the original question of this thread about the engine mounting--what I did was to mount the engine (OS 46AX) on the supplied engine mounting rails at the correct distance back from the firewall (120mm I seem to remember) and added about 4 mm for "comfort"; I then placed the rear cowling on the fuselage and positioned it to fit the lines of the top and bottom of the fuselage for appearence sake. Measured through the cowl to insure I had the required 120mm and then applied masking tape where the cowling edge met the fuselage to mark things. Next I removed the cowl and placed the engine/mount assembly onto the firewall while holding the fuselage vertical, fit the cowl on (I had already cut out enough for the sideways mounted engine) and holding the fuse vertical moved the engine around to "center up" with the cowl and more specifically the hole for the crankshaft. Marked the outline of the engine mounts and then proceeded to drill the holes in the firewall.

Mounted the engine and fit the cowl, looked terrific! Thats when I slid on the left wing....well....almost slid on the right wing! At this point, and after an open handed slap to the forehead, I was faced with one of two options:

A) Make about a 1"X1" notch in the trailing edge of the left wing to clear the engine or
2) Move the engine up about 13mm for good clearence.

I chose solution (2) and the cowling still fits pretty good. So you've been warned!

The fuel tank----why not put it in backwards and have very short lines to the engine. And even though the fuel tank is the symmetrical, it will NOT go in backwards. It's not the stopper hitting the firewall, I used a dremel to relieve the top of the former above the rear wing dowel....but it just won't go. Wound up putting it in forewards with lonnnnngggg fuel lines. Don't like it, but thats the way it is.

Ailerons-----beef up the connections where the mounting plates for the aileron servos fit in the wings by placing flat triangular plywood gussets in the corners above the spots where the screws fit...trust me on this one.

More as it gets done!