Hi, I have more then 15 years experience in web development. I worked both as backend an frontend during these 15 years. I did this kind of optimisation for multiple sites before but not always able to achieve the perfect score (some items are more server dependant then others) and so i need to ask how much control you have over the server?
My safe bet would be to move JS at the end of the page and minify&unify them as much as possible, merge the CSS files as much as possible and minify (possibly with a preprocessor like sass), improve images (these are not dependant on the server env)
I can deliver quality code as needed.
Thanks,
Adi