The blade adapters changed in 1994. A post-'94 won't fit, and nobody makes one that has the wider-spaced pins AND that will fit. I forget the details but it seems like the new kind won't fit over the Woodruff key. Also many replacement blades will not clear the plenum so its trial and error there.Don't build them like that anymore. I'd hate that dogleg handle though. Does that motor have an unusual bottom shaft length? A standard blade adapter should fit and work with a single center bolt and most replacement blades that would clear the shallow deck. Good looking mower!
Unless the crankshaft is tapered or a funny size then any blade adapter ( we call them carriers ) should fit .
The crank will be 7/8" or 1" if it was a USA model or 20 mm or 25 mm if it was an export model .
So start by getting the carrier off the crank shaft.
This will not be easy if it has not been pulled regularly and the shaft greased to prevent it rusting on.
Once you know what you are looking for there will be aftermarket carriers that will fit
Honda for metric and any USA brand for imperial
Steel ones will have the blade closer to the end of the crankshaft and aluminium ones will be further away but we are talking 1/4" so it should not make any difference to the machine in use.