First of all, go join Riviera Owners Association Engine, chassis, and some interior parts - Classic Buicks is good for ordinary stock parts, or the favorite here for performance is TA Performance As for body parts, try Desert Valley or Desert Dog Auto Parts or Speedway More Riv stuff listed in the back of "The Riview" the ROA's periodical which has a nice helping of classified ads. And then there is always Hemmings Motor News. Congratulations on joining the elite cadre of Riviera owners!
