Welcome to the forum Tom !
Dave is our prop expert and will correct any of my errors below ...
Pretty sure any LU from late 60's to mid 2000's fits Merc motors from 65 HP to 125 HP, 4 & 6 cylinder motors.
They might have different drive ratios, but you can adjust with prop choices.
Laser II props use to be odd number pitch (21P, 23P) were for V6 outboard and I/O drives, even numbers (20P, 22P) pitch were for the lower HP (125 HP and down) outboards.
New (2016) Laser II's now are every pitch, but cost over $400 !
You want a newer style with "Flo-Torq" hub and round vent holes, used ones on Craigslist go for about $200 to $250
Laser II props ...
https://www.mercurymarine.com/en/us/propellers/sport-series/laser-ii/I'm running a Laser II 22P on my boat at 52 to 54 MPH/GPS.
After testing a bunch of props, it was the best all around prop.
Below is a Merc prop chart from 1991, but part numbers should help when looking for a used prop.