I've confirmed that it is indeed a 93020-63F engine, though to federalize the car in 1985 they swapped the OEM pre-muffler with a cat. So the simplest solution appears to be to swap back for a pre-muffler and either adapt the Fabspeed muffler (ie: cap the passenger side outlet) or change-out the muffler altogether. I don't mind spending to replace "everything" and backdate the exhaust, though with an 02 bung, but don't want to be silly either. If new heat exchangers into a 2:1 or 2:2 Dansk sport muffler will give me benefit for street use (lighter weight, better performance), then I don't mind. The current exchangers have been on the car for 29 years and 98k miles (see attached).
Thanks!
