Leland,
You can check your VIN here:
RealOEM.com Online BMW Parts Catalog
Based on the VIN stamped on the plate your bike is a R75/6 European model built in september 1974 (first month of production)
You should not use tubeless tyres since the spoked rims are somewhat porous.
As for the seat cover, try here:
Moto-bins - BMW Spare Parts and Accessories for Motorcycles - Displayfinal