Opinions / Suggestions: T5 HO retrofit

[fsn77]

I've been planning this for months and it's finally time to complete this project on our 90g tank (48L * 24T * 18W). We have a 5" tall wood canopy that I'll be retrofitting the lighting into.

Here's what I've already bought:
1 4*54w T5 HO ballast (runs 1 - 4 54w bulbs, from ballastwise.com)
4 IceCap SLR reflectors
enough endcaps & standoffs for 4 bulbs

We currently keep a mixed reef of softies and LPS, but would like to get a clam and some more light-demanding corals (but not SPS). It's been up and running for almost 9 months now under 4*65 PC and 2*40 NO lighting and we feel it's time to step up the lighting so we can add some more of the things we want.

I had a plan originally to ease into a T5 retrofit (and bought the parts to do the first 4 bulbs), but after some more reading, thinking, procrastinating, and saving I've found myself not wanting to do that anymore and now have enough extra money to just buy the extra T5 parts to do a one-time, complete retrofit (thanks to my family -- X-mas).

Now, I'm thinking that I'll run 3 T5s on the normally driven T5 HO ballast (2 actinics, 1 blue+?), buy a 2 bulb IceCap T5 HO retrofit (with a 430 ballast), then wire up the 430 ballast to overdrive 3 T5s (2 blue+, 1 straight daylight?). All-in-all, it'll be 6 bulbs into the canopy, which will be a tight fit. I don't want to overdrive all of the bulbs, that's why I bought the normal T5 HO ballast initially, but now I think I'd like to overdrive the "daylight" grouping of bulbs to make sure there's enough light for a clam. I'll be installing fans to circulate outside air the length of the canopy, which is already vented on the top by design. I'm considering cutting some vents into the end of the canopy opposite the fans, but I haven't firmly decided on that yet.

Does this plan make sense?
Is it a good plan considering what I have already purchased and what we want to keep?