It appears that the bulk sales combines the total proceeds, and total cost basis.

However, due to that the land can only have sec. 1230 gain and the building can have un-recaptured sec. 1250 gain, the sale price distribution between the land and building matters, even though the total sale price is the same. 

For example, in the original problem, we have established that we have the 1,100,000 total gain, of which 500,000 is the capital gain, 600,000 is the un-recaptured sec. 1250 gain.

However, given the total price 1,500,000 remains the same, but the building price is 200,000, and the land price is 1,300,000, then we will have 1,100,000 capital gain only attributed to the land, while the building has neither gain nor loss.

So my questions are:

1 - Bulk sale and selling separately can produce different results, even for the same type of properties such as 2 buildings, is bulk sale an IRS approved method?
2 - Can you combine different type of property such as depreciable building and non-depreciable land?