I've seen a few 955 to 957 conversions done, but I am only interested in the headlights. I know I will need to replace the front fenders with the 957 style, but will the 957 headlights fit in the 955 slot?

 

fenders, holders, bumper - all new

 

Yep. That's some expensive headlights. Don't forget paint.

 

Why would I need a new front bumper? I understand the fenders since the newer lights are not as tall but the shape of the bumper along the headlight seems to be the same

 

I would do a part number check for all the parts involved. I know that the mounting brackets are different for example between the S and Turbo noses even though they fit the same fenders. But whether the fenders and bumper mate up I'm not sure. Changing the fenders may require some reworking of the brackets to mount the old bumper - or not.