If you or your builder want to know what your durations will be, download this program:
http://www.planetsand.com/programs/portmapper.zip
If you send me an email or PM, I can email you the updated application (like 200kbytes), and it has some bug fixes in it, as well as a nifty new tool that will help you figure out how to get the desired deck height.
Once you install the program, and run it, there's a button that says compare port durations or something like that. On the left side of the screen enter your current setup and port durations. On the right, enter your stroker numbers and play with the deck height to get your transfer durations within reason. Then, figure out how to get that much deck height and raise your exhaust port durations to give you a good blowdown.
Good luck