Buying an 03 KR, may have famous cooling issue

[Altekameraden]

Hello all, have a chance at a deal on an 03 king ranch. Radiator and degas bottle are brand new. He had noticed some coolant oozing from the degas cap, after reaching high RPMs. Also the mechanic who installed the new items, checked the injectors and assured him that his head gaskets were fine (methods used to test for gases in the cooling system unknown.)
I was able to hold onto the truck for 2 days, I noticed the slight scent of coolant coming from the tailpipe however no smoke, and no water condensing. When I spun the RPMs up I had no sign of coolant overflowing from the degas cap, or loss of coolant. After I turned the vehicle off I noticed a very slight barely audible hiss coming from the degas bottle cap. No sign of oil in coolant or visa verse. No smoke or problem cranking when cold. Did not get a chance to pull the EGR valve to check if the EGR cooler is the problem. Sorry for the essay, this forum has helped just seeking some further advice for diagnostics. My best case scenario theory was they overfilled the degas bottle, except for the coolant smell from the exhaust. The price is very acceptable for EGR problems. Thanks