No it will not work.
Apple introduced additional security measures in iPhone 6 and iPhone 6 plus, the Touch ID home button HAS TO be paired with the logic board. Replacing the button, even if the button is from another phone, will result in the bricking of the phone when trying to restore iOS.
There is no way to work around this, so if you would like to assemble your own phone, you'd have to:
Buy an iPhone 6,
take everything apart,
put everything back together again.
Which is a lot cheaper and easier than just buying an iPhone 6.