How to ask a postdoc professor for experimental work when my PhD experience is computational?
Your age isn't material. You have skills. Tell a potential advisor that you are looking to expand your skill set into experimental work. Perhaps your computational work can complement the experimental, looking at problems from two aspects.
Even if you are still doing mostly computational stuff in a new post-doc you will get connected with the experimentalist's outlook and start to absorb those skills. Joint papers would be a good way to get recognized.
But just ask for what you want and say why. It is perfectly reasonable. A post-doc should be a learning experience, not just a repetition of you doctoral studies.