My piece is quite small, I grow my bio hair long and mix it in. Not many people my age with so much grey, I could dye my hair but I can't be bothered with the hassle of it all, and I've been grey so long now everyone would know I dye my hair. Plus a grey piece just makes things easier...
I had the opposite reaction, grey hairs made life so much easier. Maybe you didn't realise that a lot of grey hair is synthetic so wouldnt have dyed, so that wouldnt have been an issue for you.
Going grey made matching so much easier for me and got rid of the knot problem.
Don't you think it might look a little odd having a shaven head style when your old?
I've only ever bought swiss lace, and I order from lordhair....it might be an idea to order a cheap stock piece and practice cutting the piece to desired shape, this way if you mess up it wont be a expensive mistake.
Your idea is a good one. To utilize your existing hair and site the piece behind it. Just buy a custom piece or maybe even stock system and cut the desired system. It really wouldnt be that difficult. Just make the template and cut the piece.
As for transplant, you could consider smaller...