Hey guys, I'm getting a new engine for My Kyosho Ultima ST because the old engine is running dead and instead of replacing the sleeve and piston I'm getting a whole new engine. The ones I was looking at were both O.S., the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXXA43&P=0]O.S. .12 CV-RX (S) w/10ER Rotary Carb[/link] and the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBWK5&P=0]O.S. .15 CV-RX (S) w/10ER Rotary Carb[/link]. I'm looking for more power but they both look to be nearly the same (besides the displacment) but is it worth spending the extra $35 on the .15?
I was also looking at one other engine, the [link=http://www.ofna.com/eng-picco7port.html]OFNA Picco .12 7 Port SG Shaft[/link], is that a good engine? If anybody knows any other good engines with a short shaft (I don't really care about the carb) could you please put them here?

Thanks guys! (O and sorry this is so long)
Matt