I don't have personal experience to directly answer your question, but I think a few people on here have tried scopes in the Freedom line on 458 Win Mag or similar. That should be comparable. Earlier this year I asked Leupold directly and they said that all their scopes are tested to the same impact resistance so a Freedom should be fine on a DG rifle.
Overall, I like the Freedom line and still have one on a 22, but I'm not as much of a fan of them as I was earlier this year after doing more careful comparisons of image clarity (at distance, at first light). I found that my Bushnell Elite 3500s were better than the Freedom glass. I wanted something better on my .375 so I finally upgraded to a VX-5 2-10x a few months ago and am very happy with it. However, while the clarity is better than the Freedom, I have to say that it's not dramatically so to my eyes. Based on limited experience I agree that it's comparable to the VX-2 glass, which is what Leupold asserts.
Anyway, it's an interesting idea you have, to put a forward mounted scope on an O/U rifle. I think that would look good and perhaps more balanced than a scope closer to the breach face. If you end up doing that, I'd love to see a picture.
Of the other scout scopes out there with the eye relief you're looking for, I don't know of any others that would advisable for a 458. For example, Vortex makes a Crossfire scout, and I once asked them directly about the Crossfire line and they said that while it's "magnum rated" they advised against putting one on a 375 H&H. For the combination of pretty good glass, high durability and super long eye relief, I don't think you'll find anything better than the VX-Freedom.