no i would get 4 ohm it's a long explanation but i will try. as long as they are crossed over 4 ohm the amp will fine. plus any amp can do 2 ohm stereo.
say you have a 3way passive crossover doing a 6.5, 3.5, and a tweeter the freq's are split say 850htz then 850 to 5k then 5k -20k, so with those 3 4ohm speakers the amp will only see 4 ohm's in a given freq range that is how passive crossovers work on components 2way or 3way. a 2 way set that's 110-5k on the mid and 5k-20k on the tweet the freq's are separated so it's two 4 ohm speakers but the amp see's it as one 4 ohm.
really it's best for 99.9% of people to just get a matched set of component's rather than trying to build a set because all the guess work has been taken out.
if you are going to get a 4 channel you should probably put all the door's on 2 channels running 2 ohm with the blockers and set the lowpass on the amp at around 5k for those then use the other 2 channels for the tweets with the highpass set at 5k that way you can set the gains so the mids and the tweeters blend and one don't over power the other. that's what i would do with the equipment you are going to be using.
i'm surprised toejam has not chimed in LOl