Upgrading the site

Remote work on the site. Requires the revision and modernization of the site, adding functionality to the site. We have a website (semi-online store), it is fully functional. A website has been created on the PrestaShop platform. It is necessary to transfer our site to the Bitrix platform, integrate with the 1C warehouse. The site must work with a CRM system. What we can facilitate the work... we have a fully ready-made site (donor) on Bitrix, where you can change the design, slightly finish and add the functionality that we need. Then promotion, advertising, etc. ... it is already on request ...!
**We pay for the result (there are also negative experiences in this work). We have a tight deadline. You need to do quality and time testing is very small. Additional payments are possible for the results of the work!