Hi all!
I have completed my first cc upgrade. I used a 575 mb and replaced the 680LC40 with a straight 68040; upgraded the video ram to 1 Mb; put a 2 Gb scsi drive in; installed OS 8; and got on the internet. I have a 32mb RAM stick in now and am going to try a 128 this week. But I'm also a wimp:
Couldn't bring myself to hack the cc analoge board figuring if I goofed it up I'd be dead ... so I took off the resister at 116 on the lc 575 board and did the jump at R109. Worked great! (you can get 512x36?) which is some benefit.
Now if I can get it networked 
Thanks to everyone for all their work and getting the info on the web.
Steven
If the 575 is the machine I think it is, it either has a PDS slot or a COMM slot (either CS v1 or 2)... whatever the case, you can get an ethernet card for either of those two slots.... if it's an LC style PDS slot, I'm actually looking at an ethernet card for one of those in front of me right now; I might be pursuaded to sell it if I don't need it.
Congrats on the job... I was a little more brave and had my PM6500 board with G3 card in my color classic at one point a few years ago, but coming back to the machine tonight, I can't get the motherboard to power up, so I'm at a loss until I re-read all the documentation to see what might be wrong.
As far as the VGA mod, it's pretty straight forward, and you only realize how much bigger 640x480 is compared to the 512x384 after the mod has been done.
I was worried when I read all the stuff about correcting the image and whether you have to add the capacitor to the analog board. Does it usually work without alot of post med adjustment?
Steve
I don't think so, but it's really sort of a case where your mileage may vary. Each machine has been operating under different conditions, so you don't know the full quality/capability of your analog board. The VGA mod isn't as stressfull as the 67hz "high-res" mod at least... and tweaking the display adjustments to get a good picture isn't really difficult. YOu just have to make sure you do a clean job when you modify the board, and you should be golden. Back when I did it, My picture was a little jerky once in a while; like it would be clear, then it would jerk a bit and look off-center or ever so slightly distorted... AH HA, found an old picture:
http://img263.imageshack.us/img263/2818/monitorbig2aa.jpg
but I think it was just a result of me doing a shoddy/haphazard job.
There are enough successful stories of the VGA mod that I can't imagine it not being a viable and relatively problem-free procedure.
Did you put in a secondary power supply, though? If not, then I don't know how well the analog board would fare in that case with the VGA mod and still running everything. But since I don't have experience with the Mystic mod specifically, I can't offer any personal insight on that one.
It's really too bad the "community" for doing this has kind of petered off... Back when I first got into the whole thing, there were always people around to help... I think pretty much everyone who has done this has done it, and that's that :/