Hi, I would really appreciate if you could share with me your website URL so that I can review it to provide you an exact estimation.
I assure you that I will bring exactly you want and will upgrade your website from version 1.7.3 to latest version, that is, 3.5.1, effectively ad efficiently.
TIME ESTIMATION : For upgrading your website, it would take me only 2-3 hours but matching the layout of your website with the latest version and fixing all the issues arising while upgrading the website to the latest version and testing it on all the browsers and devices will take 16-20 hours in total.
NOTE : Please let me know, number of extensions (if any) with custom coding in your website, as upgrading the custom coding will cost you extra.
Hope to work with you soon !
Thanks