Remote to Tiller conversation

[bgugin]

I currently have a 2004 mercury 15hp 4/stroke remote outboard. I want to upgrade to a merc 25 or 30hp remote.My location is at a higher elevation (5000 -7500') and changing props still will not give me the performance I desire. Selling a remote 15hp is not very practical, so would like to convert it to a an electric start tiller motor, figuring this configuration would sell faster. Just need to know the cost and parts needed for this conversation. Any help would be appreciated.
thank you

[carlinjohn]

I am sorry to say i am new to boats and dont have exact idea what all you'll need.may be some one else can help you out.