You know, after experiencing mining compared to what the calculator indicates and whatever anybody else says, I'd start a little lower than 56 drives straight out of the gate.
The most important issue at first will be plotting your drives. It takes what seems like forever. I've been plotting one 5tb drive for the past 3 days at about 5500 nonces per minute, and I'm only 65% done. I'm not even going to try to calculate how long it would take to plot 56 drives. I expect it would be a while. And, while the problem is only temporary, you'll have a lot of unused capacity just sitting around.
So, unless you are getting some super deal for investing that heavily, I'd get what I can plot in a week, then buy more (this is just me). Then, when you are about to finish with your first batch, buy a second batch.
Also, if you use xplotter (plotting software you can find on this forum), you can start mining the drives you are plotting. I've read on this forum this sometimes creates errors, I haven't had any problems that I've noticed.
Maybe an important thing to know is that I'm new to crypto mining. I've made a ton of mistakes that have caused me to take forever to plot 28tbs (5 drives). I've been at it for close to a month, and I still have one 5tb drive to go (yes, I'm slow on the uptake). That may be why I cringe at the idea of plotting 56 drives.
You'll get a ton of help here. I'm always amazed how folks will take time-out to help a stranger. But, what can I say? This forum has a great bunch of people (including, of course, myself <smile> ).
Maybe wait for a couple of more responses from people more savvy and experienced than I before making the final plunge.
I hope you join us soon.
Cheers!