Pretty sure there's quite a few wrecks that are 'virgin' out there, we've got some within a couple of miles to check out at some point
I'd guess the further off you go, the more unfished they become, but unless you can get there regularly, it could be a complete waste of time. every wreck has its day, and pootling 40miles off to find its a case of 'not today thank you' might be a tad disappointing (and expensive)
there are some wrecks that are way off that are known for being big fishy haunts, but if you don't hit em right its a waste of time
time probably better spent blasting around the inshore wrecks to find the one that wants to play
do a search for 'the graveyard'