There are a few faults with the K – the major one is that they tend to have low capacity cooling systems, so a small quantity of lost coolant becomes a big problem. The gaskets might be pap, but the fact is that once the HG has gone, you've probably done the head, and they're in very short supply.
If you can't get a head at a reasonable price, then the rest of the engine (block etc) is scrap, no matter how good it is.
By the time you're forking out for a new head or skim, you'll want a new rad, stat, waterpump and coolant, adding an extra £100-£150 to the bill. Otherwise you'll never be sure that your just replaced HG isn't going to blow again.
There's a definate owner issue too – K-series are fitted to lots of very high performance cars, and a check up here and there goes a long way, to the point that they have a very good rep in the tuning world. That said, a lot of useless duffers also buy Hondas, never check a thing, and not a lot goes wrong…