Glancing at FSA's web site, I didn't see a recommended spindle length for either crankset. If you contact FSA, they could probably tell you. Then you'd have to measure your current spindle to see if it matches either of the cranksets you're considering.

In a worst case scenario, it's not a match and you need a new bottom bracket, so you pick up a new Shimano UN-55 in the appropriate length for $15-20. Plus a bottom bracket tool like a Park Tool BBT-22 or BBT-32 if you don't have one for another $10-15.