What edge connector for prototype board?
Why not do it like in the picture you posted? 

Your prototype board already has the holes to fit 0.1" right angle male headers on the edges, and you can use strip board as the "backplane" with female 0.1" connectors.

You can get all of this on aliexpress for ridiculously low prices (like $1 = 500 pins worth of headers).

Using a card edge connector is just going to be more cumbersome and more expensive. Also the fingers on your protoboard are too short, they don't reach the edge, once you solder something into the holes they'll be full of solder, and you'll need to cut the board... or you can use a $0.05 pin header!