360 head porting for big power (500HP ?)

Did you decide which spring/retainer you are going to use? I've found a killer setup that I decided to try out this spring and so far it has been working awesome. Also picked up 3 MPH in 1/4 124- 127(so far with only 2 track passes) while swapping from a nice solid to HYD with similar specs(Normally not a swap that gains) Great price since it's for LS from the most well known LS guys BTR who probably sell the most valve spring packages these days. Saved 2.3 pounds off the springs(59.5 % less weight per) and allows way more retainer to rocker clearance. Not to mention helped allow my HYD cam SBD rev to 7400(Rev limiter set) cleanly. I'll be making a post during the winter on my findings. Here is a pick of the difference.

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Inquiring minds want to know...what is the part number and spring spec?