Yes, rotating the text by 90 degrees will introduce some narrowing for the text. There is a workaround for this though.
You have to use some other font than the default font. Then go to Look’n Feel->Text & Font->Choose Font and use the small gear icon on the font selection box.
On the popup, change the ‘Font Load Point Size’ to a bigger value until the text appears sharp. Then try doubling the ‘Font Load Narrowing Factor’ to 2.0.
You may need to tweak these font load settings a bit to get the result you are after.