I just hung up with TWM, and they believe those ports are completely accurate in their TB.  He asked what size TB I had, what engine, and about what HP I thought it was capable of.  After hearing all that, he said my 42 mm bores were simply too small, and that I'd need at least 45's.  When I pointed out that my runners were only about 42 mm, he basically said "start over" :-)   He did mention the possibility of adding a crossover tube between the two runners, to allow one to steal from the other, but I probably wouldn't do that unless I was committed to building another intake if it didn't work.