Yo, 715A would be my first choice if I was going one ball at a time.
Out of the box it has the length of the 505C to get throught the heads, dry or medium, and still have some pop on the back.
Hit it with 2000 abralon and you can tear through the oil, and still get great pop on the back.
Then hit it with 4000, polish it and it is back to out of box.
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Ken VanDalsen
Track Amateur Staff