The 8x3 will give you the most thrust. A strong running .15 will turn the 8x3 over 17.5krpm in good weather, assuming you aren't in Denver or something like that. The FP is a little older, so you will probably get a little less power.

When you go to launch it, give it a good hard shove into level flight, don't throw it upwards, and be sure to throw it into the wind. The newer SSC planes fly great, and can be hand lauched downwind, crosswind or whatever, but most of the SPAD designs don't have much wing area, and can get into a stall pretty easily.

With the engine you're using, you aren't going to be able to power out of a problem. SSC planes can't climb vertically out of sight, they aren't designed to, and if you get the nose up and the airspeed down, the engine will not pull you out of it, you'll have to push the nose down.