As far as locating a source for the latches goes, you'll need to find someone parting out one or contact a F-Body used parts seller. I know Thomas Cox at House of Camaro has two convertibles he is parting out. I believe one was a pre-89, which is what you'd need. These also show up occasionally on eBay. You may have to buy the entire frame assembly on eBay to get the parts you want. Then just re-sell the rest or keep it for a spare, since no one is making aftermarket parts for these (yet). It woule help to know that your car was indeed a ASC conversion. I've assumed that is the case in my reply. But there were at least a dozen companies doing aftermarket convertible conversions before ASC drove them out of business. More than one converter was in CA.
House of Camaro
Lon