I don't know the measurements but if you can get/DIY measure them, Moog has a list of some that may or may not include what you need.
It's a shame that BJ manufacturers don't bother to list boot dimensions and offer direct replacements, but if you have the part # of the original, I might try contacting Moog to ask what size the boot is, or if your place of purchase was an authorized dealer able to do warranty replacement, and has same part # still, get the new BJs and swap the boot from new to yours, then return new BJ and old boot for credit back, if they'll do an advance RMA replacement or maybe not even want the *old* parts back if you present a picture of the shot boot?
www.moog-suspension-parts.com
If the lower BJ, I assume it is the old style typical looking boot design (two generations ago, see below both newer generations), not the newer design lower BJ with the recessed/integrated/low-profile/whatever boot? AFAIK the newer style boot can't be replaced, but maybe that was just an assumption on my part, or maybe I don't remember them well enough and an old style boot could still be put on over, a shot new style boot?
Hmm, just noticed that it looks like Moog "might" have redesigned the lower BJ boot
again. Pic on rock auto now (left side) vs pic of what I bought 4-5 years ago (right side) from Rock Auto, both part # K8695T: