SA has a Historic Registration scheme which allow up to 90 day of use, with a log book recording usage, and the Ossa would qualify for rego under this scheme.
However to get a vehicle registed through the scheme, you have to be a financial member of a register (with the Federation) club and the vehicle must meet certian criteria in regards to originallity. Many of the federation and government is make the clubs clamp down on membership requirements and vehicle usage patterns, i.e in many clubs you are required to attend a minimum number of club meetings/events each year to maintain your membership, and there are moves afoot to clamp down on vehicle usage. This has come about due to people joining clubs to gain access to historic rego, which is quite cheap (my 1978 SR500 cost me $300 to register for 3 years), and never having any real contact with the club and using the vehicles they have on historic registration as daily drives.
Historic rego aside, I have never had any problems getting any of my bikes registered here in SA, may be it is because I live in a country area and don't deal with Regency Park. I have the vehicle ID/stolen vehicle checks done at the local Clare police stn, and sent my paperwork off in the mail to the rego office in Kadina. A week later I generally get my plates and papers via return mail. When I have delt with the rego people in Kadina in person they have been far more helpfull than the staff at Regency Park, one guy has even offered to help me by going back through the old michrofich system so that I can keep the original rego number that was issued for my 1972 Yamaha AT125 (it was only registerd for the one year in 1972)
CJ