"the idea of owning and shooting an 8-bore is so far away from my normal hunting that it just hadn't entered my mind.
Whilst it would definitely be an interesting hunting experience I think I would be massively over-gunned for my normal quarry of Roe deer and foxes!"
But, you could convert it into a .577; sell it, as truly big bores bring bigger money than smaller bores, which would give you more than enough money to buy most any smaller caliber double rifle, more suitable to your real needs and wants.