I can't imagine how much of a pain in the arse it must have been having to get that bootleg in circulation through digital track seperation. More often than not some kind soul's already done all that work for you already and uploaded to a random blog somewhere - one of a few reasons why the internet's as awesome as it can be.
Unfortunately, as you say, four tracks are missing. For some reasons a lot of Costello bootlegs I've come across aren't full versions either. I'm pretty sure that even the other Costello/Bacharach bootleg I uploaded he Royal Festival Hall one) isn't complete either. You can get each of the missing pieces from the latter though, which gives you some idea of what they must sound like, and's why I uploaded it. It's hardly ideal, but it's the closest I can get to the real thing
As for God Give Me Strength, I wasn't shifty enough to add it myself - it came with the CD of the recordings I found. Great song as you say, although not quite my favourite Costello/Bacharach tune - that'd be In the Darkest Place or the Sweetest Punch. I've been listening to a lot of Painted From Memory and the Royal Festival Hall bootleg lately as well. They were a fantastic partnership...at least when they got things dead on anyway (which to me was a lot of the time).
And talking of bootleggy things, when I've got enough time to stick around a bit more, I'll be updating the bootleg section a few more times, so watch this space!