It’s very easy to update 17.0.2 to 1.8.x.x
Here is what I did…
Backup entire site - just in case
Use Magento Connnect Manager (MCM)
Once you are in MCM check the update
Select all the updates that show up to the latest.
Let it update.. this may take about 10 min.
Your site won’t work after update… Don’t worry - Use cPanel or FileZilla change:
All Folder to 755 and files to 644
Your site now should be ver. 18.104.22.168
PS: that is what I did to my 22.214.171.124