Man,
He did a good job with the spread sheet. I will post the ARP numbers I came up with or just show how to make a ARP P/N. Pretty much with ARP at Summit Racing the numbers breakdown like this:
ARP(Manufacturer)-???(bolt size/thread count/12 point)-?

(length of bolt) For instance: ARP-611-1250 would be a 1/4-20X1.25 = 611=1/4-20 - 1250=1.25 inches long SS Polished 12 point
All these codes are for SS Polished 12 Point. ARP-XXX-?

611=1/4-20, 612=5/16-18, 613=3/8-16, 614=7/16-14, 615=3/8-16, 616=7/16-14
711=1/4-28, 712=5/16-24, 713=3/8-24, 714=7/16-20, 715=3/8=24
The last four are the length: For example the number 3750 would be 3.75 or 3 3/4 inches, Do you see the pattern? first number inches, the next three are the fraction of an inch number, They only come in 1/4, 1/2, 3/4 or .25, .5, .75
Just remember 4 digits, the last digit will always be the number zero, the second and third will either be zero's or one of the decimal numbers above without the point.
One more example for clarity:
ARP-612-4750 = SS Polished 12 Point 5/16-18 4 3/4 or 4.750 inches long.
There are no 1/8, 3/16, 5/8 lengths, just whole numbers and quarters.
Sorry if this is demeaning to anyone because of my drawn out explanation. This is done intentionally for us bike riders that did not finish 3rd grade.