206/206 have gone easy mid 10s here.. idles realy nice. works great on a stockish OR modified car.. We have a 212/212 in Melissa's car that is kinda modified idles nice an works great for her mild set up
All the above mentioned will work but the 206 with 112 is about as close as you can get to stock for an off the shelf grind. John Crawford has been about 140mph with it with unported GN1 heads. It will allow you to go a little tighter on the converter down low and peak cyl pressures will be under 5000 rpm. I never rec more than a 212/212 for iron heads unless its a solid and th eheads have been severly modded for large springs. You cant get enough spring on the irons to take advantage of larger grinds.