Advice on building "storage servers" with two DL380 G7 servers

[LMIOperations]

I'm not sure why, but our two DL380 G7 servers have two different part numbers O_o... (583914-B21 and P01227).  I'm assuming (and hoping) that these two servers both take the same exact parts.

Each server is currently configured with two 146GB SAS drives in a RAID 10 setup (running Windows Server 2008 R2).

We'd like to upgrade these to be storage servers for all of our backups, so the initial thought is that we'll remove the optical drive from each and install the additional 8-bay SFF drive cages and populate all of the drive slots (the original two drives will still host the OS, and the remaining 14 drives would be pooled into one big RAID 10 array; on each server).

Each server currently has a P410i and a P411 controller cards installed (not sure if that's a factory default setup, but it appears to be).  Each server also has two 460 watt PSUs.

I have some questions:

1. Is our intended setup possible?  If so, is it possible to use our existing raid controllers?  Would we need to order any sort of additional "riser board" or "expander"?

2. Which parts would we need in order to achieve our goal?  For instance, if we want the PSUs to be fully redundant, would we need to buy larger ones in order to provide enough power for all of the hard drives that will be installed?  Would two 750 watt PSUs suffice? (part number 599383-001)  I'm also assuming we'll need the backplane board (507690-001) and the SFF 8-bay drive cage assembly (496074-001), but I'm not sure if we also need the hard drive backplane power cable (496070-001) and/or what other cables we'll need (or if the drive cage or backplane board come with cables).

Thanks so much for whatever info someone is able to provide!