Hi,
your hydroplane has been used for .67 engines as it has an Octura solid enginemount. In my opinion you should restore it in the original pink and white colors or as in the Miller colors. If you want to go brushless it is a good choice. I have racing myself 1/8 scale hydroplanes with .67 engines and since nitro became expensive people converted them to brushless of gas. I am working myself on a 1/8 hydroplane with a 26cc RCMK engine.
Here is my hydroplane:
