I had a rag top like that ,If i remember the floor might have two sets of mounting holes. make sure they are in the same ones side to side one track maybe back a bit offset, or someone prior bent a leg not knowing which hole to be in.
69 RA III T/A Auto 69 Sprint vert 3speed ( sold to a new home) 69 350 coupe ( new home in Denver) 69 350 HO 4spd