Pillager... Exterminator... Thug... I'd vote yes for these. They're not only actually available for the time period, but they're also Star League 'Mechs. (With names like those, how did that mighty empire ever fall? Oh yeah... Atlas.)
Hoplite... Mercury... Hermes... Clint... Assassin... Crusader
BUT, to play a bit of Devil's Advocate here... the Uziel appeared in Mechwarrior 4, first. Then a TRO. While I haven't made it through all the novels yet, I don't recall it ever being piloted in any of them. So the only real link it has is in a TRO, since all Mechwarrior games are considered apocryphal. (Several designs from MW3 were exclusive to that game as well.) Since the date for the Mauler got changed a few times, and then a "new" old 'Mech was created to give the Mauler the ability to show up in the fourth Succession War, it wouldn't be difficult to say that there wasn't an early prototype version or some such, or that it had a limited run before the factory was destroyed. But it couldn't be an omnimech. Considering that being an Omnimech is really what sets the Uziel apart... Just not seeing the appeal. An IS omnimech, with a fixed engine, endo steel, FF armor AND IS weapons? OUCH. You'd be able to build a nice... MG boat. Okay, I was trying to support the Uziel, but my own ramblings sort of highlight some very real concerns as to how it could possibly work.
Hatamoto Chi, Grand Dragon, Kracken... Plenty of REALLY cool designs left to choose from. And since the timeline is supposed to have advanced (I think) we're coming close to having the Bushwhacker be available... or is possibly available... I forget the whole Somerset Striker's loophole for that one. (I like how it looks. I'm sure I'd suck driving it.)
I do want to point out how the new 'Mechs coming out are all slimmer, and have a ton of hardpoints. I still like to drive my Yen-Lo-Wang and Dragon 1N. Still do fine. Then I get these new 'Mechs with so many HPs, and the builder in me wants to fill them all... I remember when we were making do with less. Then the clanners had to show up and ruin it for everybody.
I digress. No Uziel.