Is it ok to use a tall HO building on a N scale layout? I am doing a downtown setting with tall buildings for my N scale, however I am Having a hard time finding tall N scale buildings.
In General, NO WAY!
But if you don't want to modify them and still use them you can put them behind a row of n scale buildings, situated in such a way that no train nor n scale person can be seen approaching, in this way you can add depth of field, but you can't use them track side... a trick I figured out when I was 12 or 13 was to put n scale homes on hillsides at the back of my HO layout to make the hills appear more majestic and large... and you can use the same trick in reverse, as your train disappears around a corner at the back use these HO scale buildings to create an urban tunnel. I don't mean stacking them up, but if they are in the backhground and you are using them to increase the depth of field, you can hide a train behind them, make that length a separate block with a passing siding and you can send that train out of service on a run to "McGuffin" and when you are ready for that train at your yard then send power to the siding and bring it back to the foreground.... There are ways to automate this, but frankly, I have gone on long enough... simple answer, yes there are places to use HO buildings on an N scale layout... just not up close and personal.
A McGuffin is a theatrical device it doesn't exist but it is the thing that motivates the protagonist or antagonist in any piece of literature or play.
In general no, it would look strange. Doors and windows too large.
However, I have seen a photo of an HO building modified to N scale. The builder modified the walls to divide each floor into two floors. It looked great.
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.