Thanks for purchasing a Prophecy.
I have heard rumours about people making adaptors for the Prophecy to take other speedfeeds, but might I suggest you check out the one designed specifically for it? So far it's been getting rave reviews and it is very affordable.
It's called the Empire Quick Load lid. There's detailed information about it at the start of this thread. There's also a few threads in this forum from people that already have them, and so far the response is awesome.