The WAA12L wad is for use with 7/8-1 ounce loads & would be a stretch to use for a 3/4 ounce load.
The WAA12SL has even a bigger cup & is for 1ounce to 1-1/8 once loads.
You could check by loading a shell & checking the crimp results but make sure to fight the urge to not seat the wad firmly against the powedr to try to get more column height. You'll end up getting bloopers.
My guess is your crimp will fall in the case & your shot will fall out, but let me know what result you get. Are you shooting mosquitoes with that load?