Tom,
Some good advice here already, so I'll not repeat any of it. I use a Trijicon on my 470s, both of which are fitted to me. Old eyes and fine iron sights are a bad mix for me now, go figure. There are many great Red Dot type sights out there to choose from. I recommend any quality sight that does not have to be fiddled with, a 470 is a fine Dangerous Game caliber, so get a sight that turns on with a single easy touch. If not, you may have to work to turn it on, when you need it most, or be forced to turn it on and leave it on. Some sights may power down after a certain time to conserve battery life, be aware. I would use the same argument for sight adjustments (illumination level) if that is an option, simple is better for dangerous game. Don't leave home without spare batteries if your sight requires them, you may not find any when you are afield.
On my last DG hunt, one of the guys in camp commented that he hated the look of any modern sight on a double rifle, certainly understand that position. His argument was that none of the old timers used them, so no one else should. My counter to that argument, the old timers hunted for a living in many cases, most worked to improve their craft just like hunters today, had this type of sight been available back in the day, many would have used it.)
Good luck with your rifle.