Sounds like the BB will pop lower which will have the effect of advancing your timing, which if you haven't manually advanced your timing for the new fuel already, will make your truck run better
How much it will advance it, I don't know, probably not a whole lot, but I'm sure enough to notice.
The Delphis work fine, they do not use a letter code, they use a number cataloging system, I can't remember what it is, a little searching could find it.
as far as 'letter code" preferences, if you plan on running any alternative fuels such as biodiesel, WVO, WMO or anything else thick, stick with the injectors with the higher opening pop pressures and adjust your timing at the pump.