Electric conversions are quite easy.
39" isnt a problem in terms of power or the weight you mention. You will use the steering servo/radio box/rails and no much else from your current setup.
By far the motor common and unpredictable damage is due to moisture. You must make sure the hull is easy to seal against water entry.
With electrics the cost structure is different you are buying all your fuel and pump up front - however the per run cost will be better for electric and maintenance less.
Some people go cheap - especially motors and packs - IMO this is a false economy usually the best motors are about $100 more BUT ditto for the packs - and in terms of the overall cost you pay about 15% more and get at least that back in performance.
With motors every run the runtime is longer every run the speed is higher
With batteries cheap atteries cannot perform like a good battery - they never have and never will - god batteries also have good warranties.
The extra enjoyment = a sense of extra value. The relaibility makes sure you keep having fun again and again. The most expensive element of electrics is purchasing a poor system and having to replace a part of the system.
Also as in all things experts know how to get more using less. Its a bit like a computer if you know the equipment you can choose something to compliment and enhance its performance or for the smae money somethign which slows everything down
I sell electric marine systems and can help you out - email me at