Thanks for the feedback.  I thought I'd add some notes on oils.  I found that the GL4 grade should be the target for my SW20 MR2.  Apparently the GL5 oils added sulphur which tends to be corrosive to brass ie synchros, see http://www.widman.biz/uploads/Transaxle_oil.pdf.  I noticed in a previous note that GL5 was recommended at one stage, could this have been one reason why the synchros may have been wearing out early in the SW20s?  Might explain the switch back to recommending GL4.
 
I'd also seen some comments that Redline MT-90 had some magic properties with synchros in SW20s and I wondered about giving it a try.  I tracked down a supplier in Sydney but the cost for 5 quarts was $170!  Too much and may as well put this towards a gearbox restore.