I dont want to be a jerk. Just blunt.
Your 04 isnt worth putting an engine in. Unless you are looking for a project, have the tools and the space, or you are completely tapped for cash. I say sell it to a scrapper and get another newer bike.
I tend to agree with Mike, but I can offer one possible
alternative. It is possible that you bent the valves, but did not destroy the pistons (or cylinder walls). If all of the valves are still in the head (bent but not broken off), then you may be able to save the bike with a new (used) head. Used but serviceable FJR heads typically cost less than the head machine-work that you would need to repair your present head.
It is fair to note that there is some risk to your wallet, here. There are some Gen1 heads that had a "ticking" problem, meaning bad valve guides, and you may be unlucky enough to get one of the few bad heads still out there. That problem would make the replacement head no better than what you have now. Still, a good used cylinder head (if your pistons are not chewed up) could save your bike, if you are really that determined to keep your bike going.
If you want a winter project, and can do the work yourself, there it is. Otherwise, labor costs will probably doom the project, so a newer bike will still be the better option. Pretty much everything on Gen1 bikes will interchange, so you would a have a Gen1 bike worth of spare parts, or a complete parts bike to sell. The gen2s (2006-2012) are a different breed.
If you decide to get a newer bike, I'd recommend a 2008 or later, as the first Gen2s had some glitches. The 2008s (and up) are the better machines.