The video problems are probably on the analog board. Check out the electrolytic capacitor at the top of the board - I forget what it's labeled, but it's the one which always overheats and fails. A search here will probably turn up repair advice. There may be other analog problems if sound is distorted. It's possible you have digital woes, but analog is much more likely for these symptoms.

It's possible to run the digital board without the RAM upgrade. Buy a couple of 74LS244s. They are still available through most electronic parts suppliers, and new ones are much preferable to ones desoldered from circuits. You will also need a pair of 10-pin, 5-resistor, 47-Ohm SIP resistor packs to plug into the two sockets at the head of the RAM array. Thus outfitted, your Mac will appear to have 128K.

Your Mac was originally 128K, and has had the 64K chips replaced with high quality ceramic 256K chips. The upgrade RAM board appears to be well designed, too. It's a copy of a Beck-Tech upgrade. Good luck!