IIRC the belt size is 1/2" longer than stock. (5060720)

You can always buy the 720 belt as insurance, but try the stock one first too.

For belts I'd recommend a Goodyear Gatorback or Dayco Poly/Top Cog.

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.