Is there by any chance a House/Life On Mars crossover?
If not, this is how it would work: in 2006, Mrs Tyler (Ruth, was it?) comes into some serious money (I know, plot contrivance, but sometimes you just have to), and decides the only thing worth spending it on is getting the best medical care possible for her son. So, she sends him to America, naturally, Princeton-Plainsboro to be exact.
Sam's under another doctor at first, and only interesting to House as a new model of Coma Guy, but something catches his attention - too much brain activity, maybe, and no-one knows why he won't wake up. House, being House, decides the best way to find out is to ask him. So, they use the whatever that they used in Son of a Coma Guy to wake him for a day.
Sam spills all, and I only wish that were out of character. House doesn't believe in time travel, of course, but he thinks the hallucinations sound like a lot more fun than Sam's real life, and says so. By the end, Sam agrees with him, as we know by the end of series two. However, in deference to the above-mentioned, the events of this fic take place in 2006/7; 1973/4!Sam does not remember them.
If you could work in some slash, House/Wilson and/or Sam/Gene, that would be awesome. We know Sam hears things in the coma, and there are a lot of House-vents-to-Coma-Guy fics. That's what made me think of it in the first place, actually.
In case you were wondering, the main reason I'm not tackling this myself isn't because it sounds like a lot of work (although I'm not denying that's a reason), it's that I haven't yet seen all of either series, though I'm working on both, and so feel unable to write for them.