With a GV(and enough power), 100 isnt a big deal, really. I did it once a while back on a really high speed limit highway.
I've got a Ford IDI Turbo booklet which specifies that 3800 is the limit that should never be exceeded.
That it should be governed to 3300-3600 depending on load.
On my 88, after I first put my R&D rd2-110 pump on, I hit some very high RPMs. The 110+ CC pumps are more or less "ungoverned", and you can easily hit 4K+ RPM.
However... you want to be careful doing that. I revved it too high a couple of times and found that a couple of rocker arm bolts decided to rattle loose.
I'm guessing with a properly built motor, yeah, you could probably handle 4500+ RPM, but the real problem is that you don't have much power up there.
The "crossing point", where increasing turbo boost and decreasing fueling from the pump hits is around 2800 - iit's just a limit of the rotary style pumps.
As such, generally you'll find that your IDI's dyno curve will end up peaking in the 2600-3400 range depending on turbo capabilities.