Hi ManosGR
It may help a lot if you give us more info about your project and what you want to achieve. There are many engineers on this forum who may be able to help with the 'hows' of some of what you want to achieve.
You say you want to put electrics above deck.
What electrics are they?
What purpose do you want to achieve by doing this?
I ask as there may be a better ways to achieve your goal, that one of the forum members could suggest.
For example, if you wanted to show some of the components working, you could replace some (or all) of the decks and/or superstructure with clear perspex. You could also put LEDs in the circuits to show what is working etc.
Some ideas may not be practical due to the engineering limits of materials you are using. But by putting up ideas you will get good input from experienced builders on what can be achieved.
Other questions.
What is your budget?
How much time do you have? both your deadline and number of hours per week you can spare for build time. This will effect your choice of kit.
Do you need a ship model? An alternative would be to buy a GRP hull and put on only a basic deck and a bit of superstructure so she looks like a ship. It will not look like any ship that exists, but could meet the goals of the project. This would also be cheaper than buying a full kit.
Do you have access to tools, or do you need a complete kit, ready to build out of the box? If you are not aware you will still need to buy motors speed controlers etc. (forgive me if you already know this.
There are lots of companies listed in the traders directory on here that make hulls and do kits, and provide motors etc.
Link to traders directory
http://www.modelboatmayhem.co.uk/Links/Traders_Directory.htmJust a few thoughts and questions.
All the best with the project
TT