Assuming from the description that it is a "universal motor", then just varying the voltage going to it will vary the speed. That is what is used in your variable speed drill motor for example. So what you need is a foot pedal with a potentiometer capable of handling at least 8A. 8A at 120V is 960watts, thats a lot of power for a potentiometer direct. I would go for as much more as I could find and afford though.
But that may be very difficult to find, I don't know of any. Most foot pedal pots I see now are just used as signals for something else, so they are only 2watts or so. In that case then you would need to take that 2W signal into a variable voltage controller to amplify it to the motor current rating.
Search for "linemaster variorum potentiometer" for the foot pedal, then search for "AC variable voltage controller" for the other part. You will want a minimum 8A 120VAC voltage controller that can accept an analog input of a potentiometer or voltage such as 0-10VDC, and that analog signal is what you put through the foot pedal.
"Will work for (the memory of) salami"