I have to agree with Sick Bag about the small biker units. I think two units of seven will be more resilient to shooting.
I've played orks a long time (late 90s), so my advice on this may be dated. Seeing two units of 30 storm boyz

kills me. They've always been a really cool idea, but on the board they alway ended up a huge, overpriced point sink that you
never get points back for. If you absolutely want these guys, I'd go one unit of maybe 20 boyz. Someone else may come on and say theyre the best unit.
I have never had any success with them.
What I would do with points gained from dropping a storm boy unit is add deffkoptas and some trakks/buggieswith twin linked rokkits. These cheap units have always been my bread and butter units for tank busting at range (and they fit the theme). Trakks and twin linked rokkits are in every list of mine, and I have played Speed Freaks since the Armageddon source book came out.
You could also charge deffkoptas first too and soak up overwatch when those big units hit too. Then the two big biker units would carry more weight in the assault.
Other then that, the list looks fun to play.