Using your $200K sale price and 27.5 year holding period, the gain is $140K regardless of the land/building allocation. The question is how much gets taxed at the 25% recapture rate, and how much at regular CG rates (max 20%). If the 60/40 purchase allocation ratio was maintained at sale, then $80K of the gain would be subject to the 25% rate.
Onward seems to suggest adjusting the allocation of sale proceeds such that the depreciable building is only allocated an amount equal to its adjusted cost basis. In your example, that would be zero sale proceeds assigned to the building since it is fully depreciated. This attributes all gain to the non-depreciating land and thus no recapture and the entire $140K gain would be taxed at regular CG rates. That would never fly if the building was still a functional rental. If it was an uninhabitable pile of rubble, yes.
But that's an extreme example. I interpreted Onward's suggestion more along the lines of... if the allocation was 60/40 at purchase, and you took a few year's depreciation, maybe you could stretch it to 70/30 at sale to offset the recapture. For example, if the property sold for $110K after depreciating for 5 years, and you changed the allocation from 60/40 to 70/30, the result would be no gain on the building and thus no recapture at 25%.
But again, this has to be based on actual facts and circumstances. The IRS requires that the allocation between land and building be based on FMV. This applies to both your purchase price and selling proceeds. Generally, this would be based on either: (a) an independent appraisal performed in conjunction with the transaction, or (b) a ratio derived from tax assessment values. If you choose an allocation that is drastically different from either of those, you are in dangerous territory, IMO.
I agree that the allocation ratios can be different, and there's certainly nothing wrong with taking an aggressive position, i.e., allocate as much as possible to the building at purchase, and as much as possible to the land at sale. But for me, that means, if you have 2 or 3 data sources, pick the one that works to your advantage. Don't arbitrarily assign an amount to the building which is exactly equal to adjusted cost basis to avoid recapture.