What would you do?

Howdy Catcoe --- Welcome to the forums.

As to your question, it's generally thought that the best way to make
a small fortune in Big truck truckin' is to start with a
large fortune.

That being said, do you have access to the service records of that 2002 that you're considering buying? At 16 years old, it's highly
likely that it'll nickel and dime you out of business. However, 325,000 miles would indicate a low mileage Big truck.
Cab-Over-Engine Big trucks aren't popular these days, either. You didn't mention the price, but it should be quite low.

Are you SURE the freight is there for a specialized Big truck?
Being specialized would, I assume, prevent you from hauling just any
load. But hauling niche freight could be successful, IF you can keep
the wheels rollin' --- (IF you're paid by the mile) --- and IF the Big truck
stays runnin' without a lot of repairs and/or maintenance.
UNLESS you can do those repairs and maintenance yourself.

Perhaps more details would help those with more knowledge assist you in making your decision.
And/Or, posting your question(s) in the Advice From Experienced Drivers, and/or the Owner/Operator threads.