The card with the heat sink is a Sonnet 400Mhz accelerator. They are quite rare. They came in 300/400/500Mhz. The 500's are really tough to find. 

I would clean that ROM slot but I don't think the ROM chip is required for the unit to work... I don't recall having any in my units. 

I know where you can get TAM boards. They aren't cheap but they are available.