I'm building the bike to ride, but want it to start out as good as I can make it. It'll have to earn its dents then.
I've seen a range of views about repairing old cast iron. The common factor looks to be the time and cost of repairing this head. I'll hang onto it: there may just be a series of Weld Off being planned.
As ever, thanks to all who've replied; it's appreciated!