Frankly, I don't like crosscut, except for some rare special wood species ... can't say what circumstances other than to say it seemed right at the time.
Arizona Desert Ironwood is one of my favorite woods to turn ... have turned a lot of it ... all cut parallel to the grain. . Haven't done any Hawaiian Ironwood, that I know of, but if it is anything like the Arizona wood it should be a great pleasure to turn and finish.
I assume the 8" side is the dimension parallel to the grain. . If you cut parallel to that you should get 64 pieces (8" long with about 3/4" square cross-section). . Each 8" piece could give you 3 Sierras (single barrel, either twist or click). . Or if you make two barrel pens (eg. Jr Gent) you could get one of those plus a Sierra from each of the 64 pieces. . A nice bunch of about 120 to 180 pens !! . I envy you !!
Would you mind posting a pic of that block of wood, please ... would be nice to see the color and how the grain looks.