The 300 H&H is a good buy and I wouldn't hesitate a bit on it. You can find a front sight hood of E-Bay for $40-50 if you want one. It's a great cartridge as well.
WP rear peep sight for a M71 let me know.
Most if not all of my irons are for Win 70 ans 52's, I will check if any will cross match... VB WinPoor