To the OP:
As you search for a hard tail bridge, also consider blocking your current trem system so it "becomes" a hardtail.
I have a parts-caster strat that has a blocked trem. Some previous owner did a very nice job with it. They inserted a very nice piece of wood (maple from a neck build project? Not sure) into the cavity between the trem block and the body. It fits in there perfectly, with a nice tight fit.
I can't tell you how much of the guitar's current tone comes from this blocking, but I can tell you this this strat sounds amazing. Rich, complex tone, great sustain, very responsive to picking dynamics, etc. And I don't think the trem bridge/block are all that great. Definitely not top of the line. But with the blocking, doesn't seem to matter.
You'll need to consult folks smarter than I to really judge the tonal merits of blocking a trem vs a hartail. I suspect that the extra ~ 4 or 5 square inches of contact it creates between the bridge assembly and the body wood make a big difference, but that's just my gut feeling.
Regardless, this guitar sounds great. Good enough for me to blabber on here about the merits of blocking. Look into it!