Are the 2 different styles of headliners interchangable as I prefer the looks of the latter 2nd style opposed to the first style. The 2nd style has the larger sail panels.

they would be interchangeable if you can find a donor car to get the rear mounting rails.

There are metal rails in the rear that terminate the headliner material behind the sail panel- they are different depending which version of the headliner you have.

Get those peices and you can switch to the other style.

i "THINK" You might be able to find them in the other 66/67 bop styles too (cutlass,lemans,skylark) as the roof/rear windows were basically the same design. FInd a parts car with the larger sail panels, take off the sail panels, and unscrew the rails behind them and you should be set.