I'm in the same position as you, but with a 416 Ruger.
After a lot of consideration, I'm going with a Nikon Slug Hunter 3x9x40mm.
They claim 5 Inches of Eye relief in all magnification levels and that's what really sealed the deal.
It's priced under $200 most places and that leaves me with some cash to buy the reloading components I need to feed the beast.
