Hi Michele,
I've written a message but I think I've lost it, therefore again my answer to your question:
You are right, the Revell kit is very inaccurate and parts have rather large tolerances. The Airfix shuttle stack is substantially better and also better detailed. Do you know the Airfix kit? if not, then look at you this kit conception from a German friend, those is however unfortunately only in German.
Airfix Space Shuttle & ET & Booster 1/144
http://www.raumfahrer.net/forum/smf/index.php?topic=10818.0
And this is my major real space model project (1:144), I began posting in ARC Forums, which I've started with the Crawler Transporter
Space Shuttle Launch Pad 39A with Challenger STS-6
http://s362974870.onlinehome.us/forums/air/index.php?showtopic=246711
Regards from Germany
Manfred