I am not 100% sure but it will probably interfere with the frame/engine cradle. In the Riviera the oil pan is shaped to clear the right drive shaft that goes underneath the motor to drive the right wheel (FWD). Given a choice I would use the GN pan because it is baffled and more open, the front half of the Riviera pan floor is awfully close to the front main caps ( about 1" away at best), it is really compromised to fit the Riviera drivetrain layout, also the GN pan will fit for sure. Most if not all of the 85 Riviera blocks have the 20 bolt oil pan holes so no problem there. Does your Riv motor have the front motor mount (big U shaped sort of bracket)still attached? if so and you don't want, I would be interested to buy it, let me know, also you could probably sell the Riv pan here on the board, there may be a few Riv owners interested, that also goes for the other Riviera only items, headers, crossover pipe, turbo, turbo U tube to manifold.
