Hi,
Thank you for posting your project.
I am writing to you after reading your description carefully, examining the attachments and checked both sites online.
To be honest getting it all ready within three days is very challenging but I am up to the challenge.
I can find a good theme to server as our starting point for the design make-over, and customize it to look as close as possible to the Shopify site, karenbowen.com.au.
Although to be perfectly honest, I can't guarantee a 100% style match, but I can produce something pretty similar to it.
As for integrating your Shopify products into WordPress as you might know that Shopify have discontinued their official WordPress plugin which was used for this purpose and now their preferred method is using the Buy Now buttons, so I suggest we use that instead of the iframe to replicate your Collections page.
If that sounds good to you, I am ready to get started and look forward to hearing back from you.
Regards,
Mando