I am trying to find a specialist who can help me. I run a UK business. We have
a strange requirement. We need to be able to host a domain we own but publish
another websites content to (Inside) it.

EXAMPLE: So we own abc.com (for instance) and we want to display and render
whatever.co.uk on our domain. This in itself is not so hard as we could use a
simple iframe. Our problem is we want to do something further which for
obvious reasons most browsers will deny. We want to then run javascript to the
contents of the iframe to parse and redefine what is displayed. Such as
Telephone number and change contact details.

Now in the wrong hands I can see why this would be a ridiculous hole in
anyones security as it opens up an opportunity for serious fraud. That is why
most browsers will not allow javascript on the contents of the iframe as it
fails {same origin} check. However we have the permission of our clients
(Domain owners) to do what we are doing.

My question to you is. Do you know how to be able to host a domain and display
another website along with its full backend functionality and be able to run
javascript which could alter some of the content elements?
If so I would be curious as to how much you would charge us to work on this
project?
If not  I appreciate you reading this and maybe you know someone or somewhere
I should look or talk to to?
Maybe there is a simpler way of getting this done that we are missing.