Yes, entirely possible. 60Hz is probably the most common native refresh rate for LCD monitors, so you should have no troubles there.
As to the resolution: yes, any monitor supporting 640x480 will work with the card, with one caveat.
As LCDs use discrete pixels (rather than a continuous coating like the inside of a CRT), a monitor with any other native resolution will have to either scale the display to fit (digitally stretch it out to the native resolution), or letterbox it (leave black space around the 640x480 pixels). Scaling is never perfect - you will end up with jaggy bits all over, because the pixel map of the card and the LCD panel don't match up. In short, it'll look like crap.
So yes, you are better off finding an LCD that is native 640x480, or exactly twice that, native 1280x960 - or one that can be forced not to scale, and just use the center 640x480 (or 1280x960) pixels.
/edit/ - You might also have luck with a widescreen monitor, with a vertical resolution of 480 (like 800x480, or 1600x960), that can display a 4:3 signal (ie, normal not widescreen) with black bars either side, or a larger one that can be forced to display as above.
Or ... a CRT. IMHO, this is your best bet unless you are short on space. For starters, pretty much any old CRT monitor made since the early 1990s will work (barring weirdo proprietary ones), and also you should be able to find a decent one for $0.00
When you open your SE/30, take out and examine closely the logic board and analog board for any sign of leakage from your caps. If you find any, it is advisable to wash your board/s, to prevent acid damage, until such time as you can get them recapped. Searching these forums will turn up instructions on how to wash PCBs correctly.