I have found several of the 291 heads on Ebay. They may have the 194's, but this will allow you to have the 2.02's put in and know that they are "fresh". Make sure there is some "guarantee" that they have magged the heads to check for cracks. Also, if they are for a '68, make sure that there is a hole tapped for the temp sending unit. Some of the earlier 291's don't have that hole tapped.
Hope this helps,