Gilbert,
You have brought so much enjoyment and inspiration to so many by sharing your layout. Don't get wrapped around the axles now that you have found out an error or two. Most people strive to get 10% of what you have achieved, so be exceptionally proud with what you have.
My fear would be that to get obsessive has a danger of you coming to hate PN and drive yourself up the wall striving to achieve a level of perfection bordering on the manic obsessive.
Make the compromise between what you have, what you want, what you can afford, and most of all, what you enjoy.
(I hear 4772 has some sort of GN/NE LNER significance? or is that 4472?)