the jetting that's currently in the 38 will be fine for getting it started for your 1st heat cycle.
when I went with the new 41.5 on my brand new $6K motor, it had a 55 pilot in it...it would start fine, but once I tried to crack the throttle, it would die right out, it was way too lean, there just wasn't enough fuel...I ended up at a 68 pilot. Watch for this...if you can't get it to rev up!.
once you've completed the 1st heat cycle, pull the plug and check it's color....you'll know right away what you'll need to do on the low end of the jetting...if anything at all.
Keep checking the plug after each heat cycle...
I was nervous too that 1st time after spending so much money...but the only way to find out, is to fire it off and read your plug.
you'll be fine...just go real easy until that 1st heat cycle is done....and keep the revs down until you've got at least 4 good heat cycles completed.