Your best bet is looking on the xda-developers forums to find a stock ROM. I've looked a bit but I haven't been able to find one yet. I'll see if I can do some more looking later.
Well even though I'm pretty inexperienced at this kind of thing, I can try to help since nobody else has chimed in. That is, as long you're using the Verizon version of the Trophy. Is yours a Verizon Trophy?