I have wanted to build a rifle based around my own version of something that resembles .270-257 Improved (or 6.8x57mm if you prefer), for quite some time now.
But... it would be a very expensive project.
It would be built on a long action, in order to accommodate long/heavy bullets.
And, since there's a very limited supply of long/heavy bullets in .27 caliber, I'd have to make my own. The swaging dies, alone, would cost more than the entire rifle build; and then I'd still need swaging materials and a press.
There are also no suitable wildcat dies or reamers (that I know of), that could easily be modified for the project.
Almost everything about the project requires one-off tools.
For now, it's in the "When I win the lottery" category.
I have also been wondering what to do with an 8mm barrel I have lying around, though. Lately my thoughts have been centering around 8x51R (.30 WCF necked up to 8mm). It would bear some resemblance to 8x50R Siamese and 8x51R Mauser, but that is merely coincidence.
I'd prefer something like .32 Ballard Extra Long or .32 Ideal in the 8mm bore, but I don't want to pay for a custom run of brass.
Whatever happens, the project won't go anywhere until I have an action and funding...