The 401s is going to run at 400 watts rms bridged into one channel, but that's at 4 ohms. Your subs are going to make either a 2 ohm load (wiring in parallel, like you said) or an 8 ohm load if you wire in a series. Either way, that's not going to work with that amp.
Even if the amp ran 2 ohms bridged, like it would have to, it's only going to put 400 wrms on that channel...that's 200 watts per sub. Since those subs are 300 watts rms, even if it's all the way up, it's like running the subs at 67%.
I may be wrong, but I don't see how the two subs could work with that amp.
I'd suggest something that can drive 600 watts into one channel at 2 ohms (600x1 @ 2) or 300 watts into two channels at 4 ohms each. Also keep in mind that when you bridge an amp, you often won't get double the power as in stereo mode...it may say so, but it's usually less than that.
Like this one:
JBL 600.1
Or this one:
RF Punch 601s