For the SE's standard built-in video, a PC monochrome compatible monitor was usually used with the horizontal sweep circuit adjusted to run at the Mac's higher frequency. As for the 2-page display card, that will depend on the card. There were a lot of different monitors and setups used, and back then there were no multisync displays. Everything was single frequency, and each model had its own frequency. Probably the best bet is to find a 9-pin to VGA 15-pin adapter (assuming the video connector is a PC-style 9-pin) and a multisync VGA monitor and just see what happens. If it doesn't work, then you need to see what the card is putting out with an oscilloscope and find or modify a suitable monitor.

For instructions on modifying a PC mono display, see the early Mac hardware repair manual posted on 68KMLA. I built a couple of 68K Hackintoshes, one with green CRT and one with orange, and both worked fine. I liked the larger 12" screens.

For a look at a 68K Hackintosh made from a PC chassis, small switching PSU, RAM upgrade, and SCSI upgrade: http://web.me.com/henryspragens/stuff/Slide_Shows/Pages/86_Hackintosh.html