I recommend a Triomphe or Victory Grouppo. I have seen ALAN bikes on ebay that appeared to be original that were outfitted this way. The crank has the great advantage that a 3rd ring can be added easily and 36T NOS rings are available from wwcyclery on ebay (35T from bicycle classics). What's more, if you can find a 1984 TREK 510, it makes a great parts donor for the grouppo.
Most of the Triomphe and Victory stuff is Nuovo-record compatible. This means that cool extras like titanium stuff should be available so that you can "trick out" the ALAN with superlight parts, as suggested on Sheldon brown's web site. My nuovo-record ALAN came "tricked out" with a sub-200 gm "Systeme" seat and black-anodized aluminum derailleur mounting bolt, and avocet time-trial 30 superlight tires.
If you want a modern grouppo, i recommend that you start with the "Miche SuperType" crankset, Miche's modern equivalent of Super Record componentry - simply stunning!
- Don Gillies
San Diego, CA