It's often easier to find ammonium thio in solution.
60% is just about saturated.
One would mix it down for a working strength, but yes. 600 grams for a liter.
You can make your own Am thio with sodium thio and some Ammonium Chloride too.
If you need a source for Am thio, talk to the folks who make or sell fertilizer. It's who I get it from here.
55 US Gal is about $300.
Sounds like you might have reagent grade. Far to pure for what you need.