Adding a tiller to a motor not meant for tiller steering

I gave my little brother my old 1995 25hp Mercury outboard. It was meant for remote steering - I looked at old mercury parts diagrams and this motor was one of the few that didn't have a tiller steer option. We can easily make a bracket to mount a tiller arm in. What I'd like to know is do we need to look for anything special in a used tiller arm to make this work? Do they come with different cable lengths? If so, can you get custom cables made to the length you want? Does it have to be a Mercury handle? Does it have to be a similar year (although I imagine that would help)? Any input on what to look for would be appreciated - I have more experience with remote controls, as opposed to tiller setups.

That is a very desirable motor- or at least up here in the Northeast that is a desirable motor. Especially if you have all the controls still. If it were me wanting to do what you are doing I would probably try and sell it and then use the money to buy a tiller motor. You might end up with more money to buy a better/newer motor than you thought.