Need Some Insight

Hey guys , i just picked up a holly carb from a friend. on the air horn the number reads 80457-1 my buddy said it came off his 65 mustang. he rebuilt the motor and went bigger on the carb , he says its a 600 and has been sitting in a box for three years. the thing looks new to me , what i want to know is , is there a carb kit for it ? is it worth rebuilding? and what exactly do i have?
if its worth it ill put it on my 350 chevy

Not familiar with that number but I'm sure there's a carb kit for it and they are extremely easy to rebuild. Not sure how to tell if it's worth a rebuild though because you really didn't say how much you payed for it. Usually a rebuild kit runs in the 30+ dollar range.