I "think" you need to choose the glass nose to get a level bomb site, but I could be wrong.

You are correct! If you want to have a "bomb" sight for your mission, then take the "C". The "H" does not have a bombardier position in the aircraft, as the nose is filled with various guns of one type or the other. If memory serves me correctly, the "H" saw some brief action in the Korean conflict, but not any in Nam! Not sure how effective they were in Korea,, as the ground attack of choice was the B-26C, both with and without the glass nose! The 26C was a train and bridge killer deluxe, and was a truck convoy killer in Nam.
One thing you might want to consider is the 25C or H has "WEP" available to you and is slightly faster than the 26. It was primarily designed to be a light medium class level bomber and saw outstanding service in the South Pacific area during WW2. The 25C is available with drones, as the "H" is not! It also is much more maneuverable than the 26.
Didn't mean to start a "plane" comparison thread, just thought a few things should be mentioned!