Quinn is right on! With a 7.5HP High Speed Spindle I'd go with a 1/4" o Diameter 3 Flute End Mill with either 40-45 degree helix. The best floor finish I have seen is with Helical's new H40 Variable Pitch End Mills that have a wiper flat. The Wiper Flats at the end of the tool have given us single digit Ra finishes if you slow the feed rate down and increase the RPM They would offer a 1/4" Diameter x 1" LOC Tool in their ZPLUS Coating:
https://www.toolhit.com/products/48136hel
When you talk
Or if you don't need the wiper flats then the YG Alu-Power is tough to beat, they have the sharpest cutting edges on their 3 flute End Mills. Here is their 1/4" Dia x 1-1/4" LOC Tool:
https://www.toolhit.com/products/36573
You can run either tool at 13,000-23,000 RPM and .001"-.002" CLPT.
Hopefully this helps!
Mike