I'd be dubious about 145 seats fitting.. the 155 seat back is bolted to the c-pillar.. ( "top of the wheel arch" if you like) whereas the 145 seat folds down .. so it's held in place by the realease hook that is part of the rear luggage compartment cover support.
You'd have to convert the fold-down seat into a rigid seat, since there's no way (short of fabrication) to fit the release hook doodah into the 155 rear parcel shelf.
I don't know how the 146 seat works (I thought it was a folding job in which case you have the release hooks issue again). If the '46 has a rigid seat, then that might be the best option..
The 155 is the same family underneath as Dedra and Tempra, so those could be contenders too (though I never saw too many Tempras with leather and I never saw too many Dedras, period).
But when I've thought about leather seats for my old beast, I always come to the conclusion that rather than trying to fit tired and (15 years) old leather seats from something else, it's better to go for a re-trim and hang the expense. You know it's going to fit, you can get matching door-cards and you can have any colour combo you want..