Arris rail fences on garden slope..

[ray316]

I wonder if anyone can give me some ideas how l can get some arris rail fences up on my garden which is on a slope..
I bought 6 9ft fences and posts used for these fences off someone who had took them down off his garden which was a level flat garden.
However without thinking till I got them home my garden is on a slope and the posts have V-cuts out the posts where the rails would sit in but l cannot use these has they will not meet up ..
I suppose I could buy arris brackets and put them inside the posts but the V-cuts will show up on the garden side or opposite side , also the brackets will have to be screwed into the posts where the cut outs are so l would not get all fixings into the brackets..
Any ideas

 

[ray316]

Also thinking of taking all the boards of the rails , and building from scratch putting rails up onto posts and nail boards back up... What do you think..
Would be a long job but maybe best way,
So best way to get existing nails out of the boards going into the rails and which nails to use for nailing boards back on after rails are put up onto posts.. Nails or screws.