USA Version Query

Recently got around to buying David Kerekes' and David Slater's classic book "Killing For Culture"

This movie is mentioned in passing in Chapter 4, "A History of Mondo Cinema", and also warrants an entry in the Filmography Appendix where they list two versions:

UK (48 minutes) - allowing for PAL speedup this will be the version on the region 2 DVD
USA (53 minutes)

Does anyone know anywhere this longer edit can be picked up? As it got a USA release someone probably already owns the rights for that market meaning it's very doubtful anyone is doing a USA "gray market" edition (usually a good way to pick up affordable non-bootleg DVDs/DVD-Rs of old European obscurities). Or indeed what what this extra material was.

"I think you're a load of old crap too, Mr Mulligan."