There is a better than average chance that the head has been replaced in the first place.
Put the old head in your shed with a lable on it because there is a slight chance it will be repairable for a reasonable price one day.
Usually I would see 1/2 dozen M20 heads , short a few fins at every swap meet .
If you are building the bike to look at then leave the old head there for authentic patina
If you are intending to ride it to places that are more than about 1 hour away replace it.
Those iron heads get hot enough as it is let alone when missing 1/2 their fins.
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!
