I just rebuilt my 2.6, this my combination.
Triple 45mm Dellortos
N42 head (with a little work)
Mild crow camshaft
http://www.crowcams.com.au/search.aspx?EG=58&MK=24&PC=1
Genie extractors (which had a really poor fit and needed 12 hrs work)
280ZX Electronic ignition
Hypertec pistons and Hastings Chrome Moly rings (40 Thou oversize)
Full balance and hot tank, resized rods and crank modification.
Yep i would suggest the N42 head as it has the larger valves but with compression you'll find a large amount of discussion on the validity of increasing the ratio and that it will only give a small increase for the dollars spent. You may be better spending that money elsewhere (even on a decent dyno tune).
I suppose the only problem is how worn the block is in regards to fitting specific pistons mine had to go out 1mm as it was that worn, but the engine machinist also did a sonic test on the block to see if it would go out far enough to accept 2.8 pistons... it was not advisable. At some stage in the future i'll try to find a set of flat top 40 thou over 2.6 pistons just so i can see the difference for myself, but i won't put up too much info as i'm sure you'll get a lot of good advice here.
Good luck with your rebuild.