You might benefit from the 1980's generation OrCAD VST simulator, which is a digital simulator that does take timing into consideration and originally came with substantial libraries of digital components in the "family logic" category, e.g. 74xx00-74xx999 class, along with CD4xxx-stuff, too, and a set of tools for "rolling-yer-own."

If you poke around in the Yahoo groups, you'll find it in the OldDosOrCAD user area.

I haven't fooled with new models lately, but the thing works remarkably well and, if it works in VST, then you can build it knowing it will work as you intended, though the timing may, in fact, be WAY too conservative.

RE