The Valkyries video on these computers supports VGA and SVGA (@ 60Hz), which plays really nicely with modern LCD monitors. Be wary of the Macintosh 13-inch 640x480 @ 67Hz, that does not play well with modern LCDs. I recommend if you use one with DIP switches, to set it to either 13-inch or 15-inch multimode. That will give you the greatest flexibility in resolution choices.
Now, regarding LCD monitors, anything that is 4:3 (or 5:4 if you get 1280x1024), should work okay. Probably want to get one with 800x600 resolution, as that is what your 630 will output. I have a 1600x1200 Dell Ultrasharp 2007FP, that works really well, but finding ones of those is on the more expensive side. I would go take a trip to your local thrift shop and see what they have, mine always has plenty of 1280x1024 or 1024x768 monitors for sale.
The 630 architecture is a nice architecture, I really like mine. It is the last desktop 68040 design, and has some interesting design principles going on. It supports an ATA hard drive, which means that you can pick up a cheap IDE to CF adaptor, and stick in a CF card. No need to mess around with SCSI2SD! This model has a comm slot, and an LC-style PDS slot for expansion. I recommend getting an Ethernet card. This desktop is fast too, with its 33MHz 68040. The motherboard was really designed to run at 40MHz, just move two resistors over and you get 40MHz no problem! These are certinally fast little 040 powered boxes. Note: Since you have a performa, you probably have a 68LC040 CPU installed. If you don't need to run Unix, or you don't need the FPU, don't bother upgrading, but dropping in a full 040 is certainly nice. If you do decide to go the 40MHz route, it's not strictly necessary, but its nice to put a heatsink on the Valkyries video chip, and the CPU.
Edited by Themk, 11 May 2017 - 04:36 PM.
Macintosh SE SuperDrive, Macintosh SE/30, Apple IIgs ROM3, ImageWriterBanger II. Currently building the amazing 68040! Performa (Quadra??!!) 638CD gets 40MHz full '040 , Ethernet, 136MB RAM, AV input card, and maybe something else. Should have performance comparable to the Quadra 840av when done! (A/UX doesn't work, but I still like this little guy right here: )
Love programming for GS/OS and System 6/7.