I just bought a KHS Aero Turbo ( Easton 7005). Came with a look litespeed fork and Shimano Ultegra/105 componnents.

It was set up with DT shifters and has a 9 sp cogset but I need to buy the shifters. I want to keep it retro.
I can find Shimano SL-R400 shifters which indicate that they are good for 8sp.
Can this setup for 9sp if I just don't use the smallest cog.

Thank you