While we definitely have installed gears in the L99, we never recommend anything deeper than a 3.45 for a daily driver. At the most we would use a 3.73. The reason for this is first gear. Simply put, it's so deep, anything more than those gear ratios will be a complete waste and will have you shifting into second gear far too soon. Also, traction would be severely limited in this scenario as well.
The reliability, and fun factor with the 3.45 I feel is the perfect match for this camshaft. You want to take into consideration it's broad power band, and keep the engine in the mid range a little longer.
Now for the heads. An LS9 head is not compatible on an LS3 block due to the head bolt diameter difference. Also, an LS9 head flows less (even when ported) then our ported LS3 head. Not by a whole lot, but definitely enough to make it a step backwards for NA performance. In addition to this, the valvetrain weight is a non-issue when the proper valvetrain upgrades (aka springs) are used.
I definitely think our stage 2 ported ls3 head will be the best option for this package. If you would like a lighter valvetrain, we could upgrade you to a hollow stem LS3 valve, but a titanium valve would be a waste in my opinion.