Engine intakes.

So I am still working on that B-52, However I am getting to the point where I can put the engines together, and the intakes are a little to small for me to hang on and get rid of the left over from the sprue.  My idea was to just take some styrene and glue it on there so that way I can throw it in a drill to make it smoother.  So here is my question, I now one is 5/32 and the other is 7/32 diameter, what would be the best way to ensure that they go on "square with the tubing.  I was thinking a couple of holes in lego's to ensure that there is no wobble in the drill.