I've won a working SE/30 on eBay so am going to abandon this board and get another one recapped. While I'm at it I might get the filters changed, unless there's a reason not to. Seems to make sense to get as much fixed as possible preemptively. I'm justifying the purchase using the fact it'll give me a bunch of spares for the future.

Thanks for all your help! I hope to start a post once I'm done with the refurb, then the fun starts - programming. I've ordered some books from Amazon and am hoping the C writing will come back to me (I'm more C# these days). I had high hopes for a SMB client, but having looked at the protocol I think there may be a reason there's nothing existing.