If you have a SOCKS proxy but you really need a HTTP proxy, you can just put a HTTP proxy on top of your existing SOCKS proxy.
In this example i'm using a SOCKS proxy provided by SSH and privoxy.
First create and test that the SOCKS proxy is working (superuser.com - How to check if a Socks5 proxy works)
sudo apt get install privoxy
Configure privoxy to use your existing SOCKS proxy as the upstream by adding this to the end of the file of "/etc/privoxy/config":
The default value of "max-client-connections" is 128, which might not be high enough.
listen-address 127.0.0.1:8118 max-client-connections 512 forward-socks5t / 127.0.0.1:8888 .