I think you will be OK. It's just nice to have the vertical adjustment up or down if you need it. Most of the single engine brackets that I researched prior to making my first fiberglass bracket had a transom height of about 22 inches for a 25 inch shaft motor. A 30 inch shaft motor has a bracket with a transom height of about 28 inches. Also as Don eluded to most of brackets for the big V-6's have a set back of about 30 inches to allow for full tilt up of the engine. How wide is your flotation chamber? from the pics it looks a little on the small size. It's nice to have as much flotation as possible for a self bailing cockpit on the 23 CC. By extending the bracket back another 4 inches and widening the flotation chamber you could have gained more flotation in the stern which would have also helped you get up on plane faster when coming out if the hole so to speak.
I don't mean to sound harsh about what you should have done when you built the bracket. That's not my intent...just trying to have a friendly discussion about brackets in general. You are doing some excellent fiberglass work and I think your bracket will work out ok with the way you plan to install it. It appears you have done your homework on proper mounting location of the bracket. Keep the pics coming !
Some good reads on brackets that you may have seen already:
D&D
Bracket1
Bracket2
strick