bigger SSD, more memory, best AV card it will take, should work just fine...
With the exception of just a few, minor little things:
Windows 98 cannot natively use an SSD, and no SSD manufacturers ever developed drivers for it.
Windows 98 only ran on 32 bit platforms. You're pegged to 3.5 GB of RAM regardless of how much you put into the system.
IIRC, Windows 98 peaked around the time that AGP graphics were all the rage. Since then, no graphics card manufacturer has ever developed drivers for Windows 98. If you can find an AGP graphics card laying around somewhere, you'd be hard pressed to find the drivers on a legitimate site.
And, of course, let's not forget that Microsoft's support of the OS is long since gone. You can't patch the OS. You can't protect the OS with any A/V or malware scanner. Windows 98 is notorious for being very chatty over legacy communications protocols that, if exposed to the Internet, will see your system compromised in less than 5 minutes.
But, by all means, use Windows 98.
FWIW, if you use Windows 98 in an unconnected configuration, it can play legacy games (looking at you FFVII) without skipping a beat. Otherwise, I wouldn't touch it with a 10 foot pole.