These are the dimensions of that box if I'm not mistaken.

Box Dimensions:
Length: 33.75
Width: 19.38
Height: 13.38
Weight: 7.00

If so, then it is pretty close in floor size to a cb70 which is:

TUB SIZE 33.5L x 17.75W x 6H

I think that size would work up to about 4 feet. You can basically tell just by looking at the snake if it looks too cramped in there.