Heres my latest, the beaver converted to diesel, thats an Enya Ss25 diesel in the cowl, this is a very very well thought out, high quality airframe, conversion was pretty simple sawed
off that little box on the front of the firewall, glued on an 1/8 ply firewall to the old one the 2pc great planes mount even lined up with the trapped nuts in the original fire wall this is a big plane 68" span wt about 5.5 lbs it came in lighter than the electric which is stated to be up to 6.2 lbs, It should easily handle a 40 glow . I used 225 Hitec servos for all controls and a sub micro for throttle, went to 3 1/2 main wheels 1 1/4 tail wheel and added the door outlines and steps. all tail surface controls are inside nice along with the flap controls only the aileron rods are outside martin

the OS32SX ( just got one would be a good choice same bolt up pattern and no cowl hacking just that hole in the side of the cowl and small hole for needle valve extension
there is more on this on the Diesel site under beaver