[kenikh]

Albin's out of Australia is probably the #1 provider of aftermarket gears and can make pretty much anything. If there's room, you may be able to get Albin's to cut you a custom set of 3rd gears, perhaps in a stronger steel alloy or with fewer total teeth on both sides (same ratio). This would result in stronger individual teeth, with the downside being fewer teeth to spread the load over - this last suggestion is just wild shot in the dark though.

Straight cut gears may be stronger, too. Some suggest that cryo treating gears also makes them wear better, as well as some suggesting TFL coating the gears (I don't buy it).