If it was me, id have ten and some sort of ballast tank. You NEED a 20 inch mid BTW. That is necessary.

I'd prefer tabs than ballast, both is even better. I have both, started with just 200L of ballast up front. After a season I got dana hp1100 tabs, man did it make a difference. The tabs work quick so you can change things at the drop of a hat, the ballast obviously takes a minute or so to fill and empty. I still like to throw a little ballast in if its the sort of water where you can run fast with trim but the boat is getting unsettled on some smaller waves.
30" shaft is way to long, as mentioned a 20" would be better.
It's a wild looking setback you got on there now! All depends on the hull weight to say what setback would be ideal?

actual it looks like a 25" engine. Although it will put the center of gravity higher you can mount a hydraulic jack plate on it and it would help the powerhead/transom clearance when it is in trailer trim. My 22 velocity had a 225 excel yamaha(more like a true 175 hp) on it and was able to spin a 23 raker prop for 64 mph. without triming the jack plate it would run 55 mph. http://miami.craigslist.org/mdc/boa/3618694826.html

Weight should be pretty similar to my Challenger, I agree on tabs but these boats run so high on the pad mounting the tabs is tricky. Not to mention big bucks. 20inch mid is necessary for racing it. Even if it takes 10in of setback to make work

Hydraulic Jack Plates work great for recreational boats, but not so well for race boats. You rarely see one on an offshore race boat.

Pretty sure that is a 25", if it were a 30 it would have a spacer in betweeen the mid/lower.

Here's what a 25" mid-section looks like on my 1992 Mercury 200:

Cant click on your pic to blow it up, but it looks about the same distance from the lower mount to the cav plate as his. My guess is 25". If he is gonna run 10" setback, he may even want to go 20". Only problem with that is it actually will lower the powerhead, and give him more trouble with his trim issue.

Sorry about the pic. Not sure what happened there. Kevin used to build all of the 22's with a small splash well like mine has. But this required a 25" mid-section so the cowl didn't hit when you trailered the motor up. He will make them now with a cut down transom that allows for the use of a 20" mid. Of course if you run enough setback, the cowl won't hit anything anyway.

I think we're on the same page, run a 25" with as little setback as necessary to clear the transom.