Hmm…the H.225 protocol was built with Q931 in mind. I know there is definite guidlines for SS7/C7 interworking with ISDN. Please see Q.699.
Of course SIP-T is fully compliant with ISUP, you encapsulate the whole ISUP message, what is the big deal with that. H.323 was built with TDM in mind, and was built as a way to replicate some of the tdm infrastructure using packet based mechanisms. SIP is an entirely different approach, but the fact that you could have a MIME encoded body in the message allowed the ISUP transport.
BTW…what is ISUP v3? never heard of it…is it one of the red, white or blue specs?
Another note ISUP has parameters, ISDN has information elements. it also sounds like you are a proponent of ISUP transparency. I would like to know what full ISUP transparency gives you and why folks believe it is a complete requirement. What are the effects, inaccurate billing, poor feature infelction?