Over the years, I have used...
AutoDesk Inventor-->Good learning program but that's about it.
Pro/ENGINEER-->Excellent, very powerful.
Solidworks-->Same as Pro/E but I like the interface much better.
I currently used Solidworks as I have a free, legal copy of the student edition with full COSMOS capabilities.
Regarding a reverse engineering company, I recommend these folks:
http://www.adcinc1.com/
A close friend of mine at Purdue had some cylinder head scans done by them about a year ago and was nothing but pleased.
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