Both of you are right to think that's two different boards which has been described in the above lines. Best is to scroll the right volume to fit your weight in the Speeed list of available shapes, rather wanted to order a customized length as you did want to do.
As well Speeed and 10-6 are different boards , scroll the 10-6 list to find the right one for you. Bert did a accomplished job...don't change anything else.

When SoCalGremmy ask me for a design, I pull out first my 6'8" to 8" picking some tendency toward some cruising board and accidentally that's looking (still a the bit far ) as a Speeed.
The Speeed is so shape logic in its kind