Can I put BBP drums on my 69 ?

It would require some of the same stuff you'd need to swap to discs.

The B body drums are the only bolt in ones with stock parts. NO A body cars came with big bolt pattern drums.
To do the B body drum swap, you'd need either the 73-76 A body DISC upper control arms (Which use the B/E larger upper ball joint) OR get the adapter/spacer/shim kit from Dr Diff to retain the smaller upper ball joint UCAs. You'd need 73-76 A body DISC lower ball joints too.