That schematic is the final version of the isolator (the version .3 referrences were to the ammeter it was isolating). I've put that very circuit in into a couple things without problem.
The choice of transitors is very forgiving; I used some bog standard SOT-23 packaged, type 2n3904 and 2n3906 that I had around. The resistors can easily be the common 1% tolerance, tenth-watt 0805.
The only thing that might give folks problems is the 'optional resistor'. SMBusses can use either 5V or 3.3V signalling. 5V devices will function correctly with 3.3V signals, so I made it 3.3 on the slave side. On the master side, you have to match the existing signal voltage (easily checked with a multimeter). A jumper would be way cool, to make that selection easier.
I'll take a couple of the isolators if they're separate.
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