Hi again,
Looks like it could work, but you should do a simulation and make sure it works the way you want it too or else ask someone else to do it for you. You also have to check power dissipation in the components for various conduction angles so you know what ratings for the parts.
Ok, another thing is that that circuit is not able to provide conduction angles less than 90 degrees. This is typical of very simple circuits like this. That means the speed will only go down to a certain amount and that's as low as it will go. This is ok if you dont need to go to lower speeds, but not ok if you do. You can help the problem a little by introducing some capacitance but then you loose the high end.
This is exactly why circuits have moved to microcontrollers and other types that use some sort of one shot like timing where the trigger pulse is sync'ed to the line but is delayed by the amount determined by the pot, and it can be continuously variable over the entire 180 degree range which means you get a full speed range adjustment from zero to full speed.
Is your line input 120vac or 240vac?