The SIP VRAM is a dead giveaway that it's a VidCard . . . what data is printed on the SIPs . . .

. . . paucity of MoBo connections makes me think might be getting its power a/o ground from another source . . .

. . . trace the connections on the MoBo . . .

. . . I'm guessing that you've got a 5V connection and two signal lines . . .

Does the Classic have a dedicated Video Controller or is it all a function of the 68000?

< WAG >

I'm thinking internal grayscale and all you're missing is a custom Y-cable placing that card in between A/B output and the CRT input.

I'm also guessing that 5V is the only thing missing on the original cable.

Could be 4 or 8 level grayscale given those two(?) signal lines, depending upon what's available on the CRT connection cable.

Anybody got the SE/30 schematic handy? :?:

< /WAG >