HI Boatvolt
I see you are over the pond in the USA. I would agree with Haverlock's advice.
You have not said what motors are installed and what battery power you will be using? My motors from the 1960s were not very efficient and some used an electro-magnet in place of fixed magnets. The former are not as friendly to modern ESCs so it would help if you could post a pic or give details, please? I am not familiar with this US model so some details re length/breadth/ weight and prop size would be useful.
I suspect the original control was full ahead and full astern so a modern system will make the boat much more controllable and fun to sail.
Dave

weeeeeeeeeeeeeeel I guess you could refurbish your controller but honestly the only way your controller could work is to use resistors to control speed and that is VERY wasteful of battery power.

Since your motors are brushed a couple of esc units will control your motors they are not expensive and will Improve things out of all proportion.

Since you will be using the bec ( battery eliminator ) disconnect the positive line in one of the esc servo connector. Then use a "Y" lead to connect to your receiver.