Jeep Wagoneer Oil Burner

Recently purchased a 1979 Jeep Wagoneer - 360 Auto 4x4. Has 83,000 original miles and has been well maintained all its life. Previous owner installed a cam kit , alumin intake and Holley 650. Radiator went bad about a year ago and he overheated the engine.

Vehicle runs nice and does NOT smoke. However it has gone through 3 quarts of oil in 400 miles. After removing valve covers, inspection reveals that top of engine is extremely clean. There is somewhat of a burnt oil smell. Removed one valve spring. Valve seal is rock hard but not cracked. There does not seem to be any play in seal travel or valve. Inspection of spark plugs shows consistant Ash deposits on all plugs.

Question: My mechanic claims that a leak down test will really not reveal, without uncertanty, if rings are bad. Suggests that engine be pulled and broken down. He believes that the rings have probably been overheated and that engine needs rebuild or replaced. Will a leak down test indicate with out a doubt weather the rings are bad? He claims a leak down test will not tell the whole story. This vehicle runs so nice, I would of course rather replace valve seals than rebuild whole engine.

Thanks!
D.B.