Not knowing much about either Derbyshire or chambered tombs, I'd not feel able to comment on those stones. Are there many such things in the area?
It seems positive that the archaeologist you mention could be interested in having a bit of a dig. Hope you find out more.
Never been on that side of the Monk's Road, but there are certainly tumps up there (I think I added one called Cown Edge). There;s also quarries with weird blocks of stone. I'll try and have a wander up there on Sunday - is it easy enough to find if we get to roughly the right place?
sam