Will I need to make any mods so that one of these things will hold at around 60 degrees?
Just get a temp controller.
They are inline with the power cord to the freezer. You just pop the temperature probe inside the freezer and it switches the freezer on and off.
Where can I find one on line and how much are they?
I know I could probably google and find something, but I'd prefer a tried and true brand from someone who uses them.
Do a search for "temperature controller" and you'll find many posts about the different ones available, makes, models, etc.
"Science + beer = good!"
Ranco, Love, Johnson Controls, etc...
morebeer.com has the unwired Ranco for $65 with free shipping.
Before shipping, I'm sure. I'd rather give my money to a reputable home brew supplier anyway.