1998 Subaru Legacy oil burning

I'm interested in buying a '98 Subaru Legacy GT Wagon with 137k miles.
It's a beautiful car, well maintained, original owner, garage kept, has all the records.

The owners replaced the '98 engine with an '02 engine because they heard there was trouble with the '98.
The '02 engine has 64k miles and was put into the vehicle about 1 1/2 years ago. Also at this time the owners replaced the brakes, installed new clutch and replaced the timing belt.

It all sounds good except when he told me he adds about a quart of oil every 800-1000 miles. He said it doesn't leak (evidently burns).

I really like everything else about the car, but should I even consider this car?

Thank you!