What are the best replacement valves for the 440-1 heads. I was getting ready to pull the heads off my 440 drag motor and send them out for porting when I remembered there was a weird popping sound from the left header on cold starts the lest few times out. I figured it was a plug starting to foul since it cleared up after warm up and the car was still running consistent 6.26 @ 110 1/8th mile. It even ran a best ever in some really good air 6.11 @113mph. I ran a compression and leakdown test before pulling heads. All cylinders were 210-220psi compression except #7 only had 118psi. Ran leakdown on #7 and it had 85% through the exhaust. Checked lash and #7 had 0.010 less than the rest Pulled the header and couldn't believe what I was. The # 7 exhaust valve was cracked 3/4 the way around the stem I don't know How it stayed together. I feel VERY LUCKY!. I was told by one of the head porting services the valves Indy uses are not very good and that the would tulip and break with roller cam spring pressure. What are the best replacement valves, Ferrea,SI, or something else?