A lot depends on the BCD measurements of your triple. If it takes 110/74 bcd rings, then you're in luck as rings are readily available, old or new. 110/74 BCD was pretty common back in the day esp. for Japanese touring bikes. Pics would help of the crank.
Measurements would be really helpful,
Sheldon Brown's Bicycle Crank/Chainring Bolt Circle Diameter Crib Sheet