Sale of real estate by a church is it UBIT or not?

[BurtonCPA]

Several years ago a church purchased two buildings that sit on 43 acres of land. The larger building has always been used as the church. The smaller building with its 3 acres has been rented on and off to other businesses and rent, when received, has been reported on 990-T as UBIT. Recently the smaller rental building with its 3 acres was sold at a gain. I'm looking at this article about letter ruling 9651014 and wondering if this income may be excluded from the computation of unrelated business taxable income.https://www.churchlawandtax.com/legal-developments/sales-of-church-property/

The building and land were held for 6 years before being sold. The church has never before sold real estate. The management activities with respect to the property sold have been minimal consisting of collecting rent and providing routine maintenance and repairs. The land and building have not been improved in any way and no services have been provided to tenants.

Further complicating this situation is the fact that the property was acquired using debt--a mortgage loan; however, would it meet any of the exceptions to being deemed "debt-financed property?" Based upon acres, only 3 of the 43 have been rented and subsequently sold so would that mean that the 93% of the remaining property could be considered as "being used for exempt purposes?" What does "being used" mean? Much of that 40 acres is just sitting vacant. It is not for sale, but there is not currently money available to develop it.

What is the correct treatment for the gain on the sale?