SSCX Only!

You should be able to get a 41T for 144mm BCD.

Here's one http://www.sjscycles.co.uk/ta-144mm-bcd-5-arm-old-campagnolo-chainring-prod195/

43T (42?) is about as low you can go on your highschool teacher 144bcd.

41 is the absolute smallest, but you're unlikely to find it. 42 is probably common enough. Bear in mind you probably don't want to be grinding lots of mud and crap against your fancy dura ace crankarms with your chunky mtb shoes though, and Alfine chainsets are dirt cheap.

I had a goldtec 42 and was happy with it on my pomp.

Whoa. Quick and comprehensive. Thanks very much!

You make a good point Tom. I hadn't considered that.
While I'm not that precious over parts, and they were second hand to begin with, I suppose it could be a shame to ruin them.

I guess new cranks would give me wider choice over chainrings too..