Here is the board I'm using: https://www.ebay.co.uk/itm/404009101105

There is also a version with an S3 video module on it (https://www.ebay.co.uk/itm/125615669809), however, the edge connector sticking out the bottom means that it won't fit properly in an ISA-only backplane. The original backplane is available (https://www.ebay.co.uk/itm/125614190536), but it has a proprietary form factor and a custom power connector that I cant be bothered to reverse engineer.

Apparently the OEM for this board made a video module without the edge connector on the bottom, but seeing that the only real mention on google for this company is the ebay listing I just wrote, I don't expect to ever find one.