Hi,
(I hope bad/ill-informed help is better than none...)
I hadn't heard of Simple Packaged Crystal Oscillators (SPXO) until the datasheet of yours I think, thanks. Interesting.
Description from
SPXO, "SPXO is the simplest Crystal Oscillator with no compensation or control of temperature made by combination of a crystal unit and oscillation circuit. SPXO, especially small products used for clock purpose,"
Hopefully better performance if all components are onboard that IC already; discrete version will have hot and cold spots and corresponding drifts up and down etc. so could never be as "good" as that IC. Crystals need love and stability and ovens even sometimes and however much you put into it, otherwise they'll just be okay, like any other component. Still think that IC will outperform a discrete version.
I'm guessing you want to keep the paralleled inverters as a buffer? I'd be careful, that's a CMOS output and there will be level discrepancies into a BJT package like a 7404 - I'm assuming that package is BJT. On the other hand if you're operating it at 1.6 - 3.3V max. I suppose that won't be much of an issue.
Just in case An identical CMOS inverter is CD4049UB, specifically UnBuffered, however CD4xxx datasheets all say 15MHz max. at Vs or 5MHz at 5Vs...
Maybe the buffer as inverter isn't needed and a (dual) MOSFET totem-pole could suffice as a more powerful buffer instead, anything fast enough really.