Here's a option with all the others heads mentioned. Rhs make a very good head in 160, 180, 200cc you can buy a set ready to bolt on for about a 1000. Before spending the money on cast plus a valve job and new springs. Look to see what you can get in aluminum. Check out skip white on eBay. He does a lot of different brands of heads for sbf.
Good ol Racing Head Service..
I still remember when that was a shop in Memphis and the area was a HOT BED for performance.