Joe,
I don't understand your comment that it will be some time before you'll be able to buy a Jab or CAMit engine. You can place your order for a CAMit 3300 engine at 8:30 am Monday morning, and if Ian Bent doesn't have one on the shelf I woud bet he'll have one built and dyno tested by the end of the week. Have you actually spoken to CAMit or just looked over their web site? As I said in an earlier post, give him a call or email him. Get his view on when you can get an engine.
I don't know if or when there will be a Jabiru 3310 engine. You'd need to talk to Jabiru and see what they can tell you about that.
Cylinder corrosion can be a problem in any engine. You'll need to take appropriate preventative action no matter what engine you use.