The reason why so many Boss 429 mustangs were around with very low miles also...Hey people, that Jim's 131 is a race motor. Lasting for 10000 miles was probably of little or no consideration when it was designed and built.
It had one job, make as much power as possible, till it breaks.
Go buy a SB2 from Hendrick's and put it in your cruising car. See what they have to say about it when something craps out after 1000 miles.