Please have a look at my Profile Page for a taste of my skills.
Since I am not fluent in Spanish, I'd get myself the services of a Spanish speaking assistant to do this job.
You said this is for your future generations, and not really for commercial purposes. But, after its completion, if some Hollywood producer reads about it by chance, well who knows? Another Titanic!?!
But, I'll make the story, as addressed to your future generations, children and grandchildren. I'll make it a personal story, that they all shall be willing to read again and again.
And, maybe pass it on to their children too!
Besides this, I can offer you a Book Proposal of this job. It will explain how the book is going to be done,and what are all the things that will be there. It would be just $50, and will help you decide.
Regards,
Faithstar