I recently picked up a very nice condition Israeli surplus FN Mk II Hipower from a local seller.  I thought $425 for any usable Hipower is decent price.  I replaced all springs, cleaned up the firing mechanism and kept the magazine disconnect and got a very clean 6 lb. trigger.  I've fired 300-400 rounds and it works great and is fairly accurate.  One problem I have is the original sights.  Due to my poor eye sight it's difficult to see the small factory sights when firing rapidly.  I don't have as much problem with my Mk III with it's larger/taller sights.  
I would like to have a new sights put on the Mk II...something larger/taller on front and with wider rear notch.  Couple of my 1911 pistols have the Heinie Strait 8 sights which I like and can still see okay so something similar would be good.  I also heard Novak's Hipower sights have large profile but I've never seen one in person.  Any suggestions on which sight would be ideal?  Also any recommendation on someone who can install it by just sending in the slide instead of the while pistol?

Novak's hands down. You can send only your slide in, no problem. Call them and tell them your needs and they'll set you up. Very fast turnaround time.

https://www.novaksights.com/