value adjustment for short tbo on cam

I'm trying to figure out what's an appropriate value adjustment to an
engine that has an upcoming tbo on the camshaft.

Engine: IO360 C1C Lycoming

Engine was torn down in 2002 (prop strike inspection), new lifters,
new valves, chrome cylinders honed, new rings, about 400 hours ago.
Camshaft at that time was pristine. Time SMOH is about 1200.
Compressions are all in 70s.

What kind of value adjustment would be reasonable compared with an
identical engine with a 2000 hr camshaft tbo?

Is there any way without disassembling the engine to determine the
current condition of the camshaft?