This seems more natural to me: I've attached two files that I'd like you to record when you have time, although there are a lot of volumes. You don't need to read them all; you can just choose which you'd like to read. That would still help a lot.
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Mister MicawberThat would still help a lot.And, That could still help a lot.
That would still help a lot.That could still help a lot.
H MI used "Although" to mean that even if you don't record them all and choose which you like to read to record, it would help a lot.It seemed the wrong choice. That is why I suggested the revision.