Specs on Horizon:
saito 180:
Mounting Dimensions:138 x 69 x 135 mm

saito 220:
Mounting Dimensions:194 x 75 x 158 mm

I have both motors, 180 in KMP ME-109 and the 220 in H9 1.50 P-51. I can tell you for a fact the 220 is bigger which agrees with the mounting specs given by Horizon. The 220 may be "packed" into a 1.80 size case, but the prop shaft is longer, the mounting flanges are wider, the mount holes a spaced a bit farther apart, the cylinder head is higher etc.

Hopefully the mounting dimesnions above will give you the info you need in order to determine if it will fit in the plane.

here's another option, thouhg more expensive.
Saito 200TI twin inline
mounting dimensions: 160 x 110 x 142mm

Length wise its right in the middle of the 180 and 220. Width wise, its wider, but there's plenty of space this way in the CMP 109
http://www.horizonhobby.com/Products...odID=SAIE200TI