I would say mid to upper mid teens.
I have a silver blue 82 with 170K miles on it, but rebuilt with things like:
Rubber air dam
Both headlight actuators - headlights are all new
Radiator
Water Pump
Stainless steel chrome top radiator hose
Chrome water neck.
Water pump - in last 4 months
Washer pump
Engine - LM1 - rated at 250 - probably about 225 in the crossfire. Uses NO oil - Mobil One from the outset. New sensors all around, but see below for two changes I did.
185 degree fan switch
Mid-80's Coolant temperature switch
Port matched intake - standard mod everyone says to do - which turned out nice.
3/8" CNC milled aluminum TBI spacers.
Fuel pressure guage on front TBI
700R4 transmission rebuild to current standards when motor replaced.
Power steering pump - last 4 months
Control valve - last year
Power steering pump hoses
Alternator and lower alternator bracket
"Specially designed" dual, free standing, K&N air cleaners with K&N lids
CVR Protorque high torque starter wrapped in heat blanket - you will NEVER have heat soak starting problems!
7 blade fan from a mid 70's - not the stock 5 blade
Master cylinder
Power Booster
All rotors and calipers (parking brake needs rebuilding - it drags some when you put on brakes and gives a squeeling noise some - traced it down to this, just have not done it.
Magnecor wires - $160 set - 6 months old
ACDelco Platinum Rapidfires
DUI High Output coil, cap and rotor
Dynamod
Windshield - about 6 months ago
T-tops, with new rubber, and the dot matrix liners Car does not leak at all, anywhere - unusual for a Corvette?
Tach circuit board - last summer
Sanyo radio with CD and tape - new one year ago.
Rear Antenna - last summer
Font speakers - have to look up brand - same time as antenna
Rear Alpine speakers - I would put in a booster, I think
Carpet
Door sill liners - have but not in now
Thermal barrier under carpet, seats, tranny tunnel (over its top also), behind seats, trunk.
Not new, but a/c serviced all the time and will truly blow cold, and keep you cold even in the 100 degree summer days
Al Knoch leather seats
Poly differential donut - u-joints checked at same time, they are OK
Brand new BFG Radial T/A tires - probably 1,000 miles or less - in back. Front are about 1 year old. Show very little wear. Had total alignment done about 2 years ago.
New catalytic converter last fall - Car Sound high performance - flows better than Random Technology
Borla Mufflers (now where did I get those?)
85 fuel pump - flows better than the stock 82 - can support higher fuel pressure if ever needed.
Viper alarm
Lumar metallic tinting - redone a year ago. Will not turn purple because of the metallic content.
Battery is an 8 year battery with about one year on it.
I had a friend looking at it and came close to paying over $20K easily, before he talked me out of selling it, if you can believe that.