I have used the 38 air striker on several bikes, I bored mine to 40.5 mm. I like the airstriker because it is much shorter and moves the slide closer to the piston, great throttle response. You will have to build a neck on the back of the carb as it is probably 1/2 to 3/4" shorter.
What is your reasoning for going to the 38mm? I've been using the Lectron one one of my bikes, but they seem to be dependant on what you have in your motor as to how well they work.