Wow nice, i also had those ideas . I even made plans how to load and fire guns multiple times, when i was a kid.
But if i where you i would take the smallest ship possible so your scale would not be too small even when its a 5 foot long vessel.
Because of the fact that the cannons will need a lot of detailled work especially when you want to be able to raise and lower them. ( u will also need to make 3D plans for it and be 1ble to forge them)
I must suggest if you never have build models before or little mechanic pieces, you must first try smaller models to increase your skills and learn that those projects can take like around 5 years to complete... (trully)
What u also could do is firST build it the simple way and then after if STill not satisfied, you could modify it as you wish.
I sencerelly hope you would find a way to build it and complete it, becaus there arent that many projects in this world.
I only occupy myself with ww2 models and wooden ships. Maybe when i am a bit older i will do a project like yours because i already made primitive plans for it