Be VERY careful with Chris Barrys AC kit. The bracket allows the stock Rover AC compressor to be used, which is all fine and well, but it uses a TINY daihatsu charade alternator, i think its around 45 amps, IMO no way NEAR enough to drive even a stock engine. The stock alternator on the k20 is 100amps.
Now, I am an electrical engineer for an automotive OEM, and 45amps is stupidly small, you will be running on the limit by simply switching on the headlamps and if i remember doing my calculations if you had the high beams switched on; the battery would no longer be charging. This is on a stock engine stock chassis setup.
Think about how much more current than stock simply your pumps are drawing. Anyways, I rant.....
Chris is a great guy and very very helpful, but on this point I totally disagree. If you could get a daihatsu charade alternator built to at least 100amp spec then it would be great IMO