I'm not really sure what you mean by this. Of course an aftermarket aluminum head will not be factory spec. There are several aftermarket aluminum heads that I would consider factory replacement and all of your stuff will bolt back on without issue.

Some aftermarket look like factory, some do not, some have angled plugs, some do not. There are a few different combustion chamber sizes available too.

This will be a great opportunity to for you significantly up your engine performance by simply making a good choice here. It will be difficult for us to tell you what that is without knowing exactly what your goal is. If it is to simply look as close to factory as possible, 440 Source's Stealth head is an option.