[Healeys] Valve guides

[john spaur]

I checked the archives and there was a post saying not to use bronze 
valve guides in a cast iron head. My engine is basically stock.

I noticed two there are two different valve guides; one is cast iron 
(stock I presume) and the other is manganese-bronze.

What material should I use for the valve guides.

What is a good source to purchase them from?

Thank you,
John Spaur
'62 BT7