If I was in your sitution I would dich the KNS80 and fit a small DME and leave the KLN89B fitted.
This would leave you a lot of panel space for you next move to some sort of display that would do the map thing a lot better than a GNS430.
The DME I would recomend would be the KN64 as with the GPS you dont need the extra range that the KN62A will give you and it is cheaper.
The KN62A is the best bit of kit that I have ever fitted in 25 years I have never had to send one back to the avionics shop to be fixed (I have owned two) and if you are high enough it will lock on at 100NM+.