lyndon i have reason to believe the sv25 model 4wd camry (only found in the US i think,but has S series trans) has a 0.73:1 fifth set that will fit an S54.... every other avenue i have looked at has drawn a blank,wiki says celicas are 0.73 but its bullshit as the EPC says its the same part number as the mr2 cogs.
Im going to bite the bullet soon and order them from toyota,it might cost a few hundred quid but it will be worth it if we actually find them