Seeing this in the RJ&E Bundle was a real blast from the past!
I actually have a physical version of this from the 80's (that I managed to rummage out to confirm that it really is the same thing). It doesn't seem to mention the name Tangram anywhere (it's a "Hi-Q Puzzle" called Pythagoras and the pieces are green plastic) but it does come with a fold-out booklet with 179 silhouettes and a lot of them are different to the ones here - certainly the letters and numbers are and I reckon a lot of the more abstract ones are as well.
This has me wondering if a scan of the booklet would be of any use/interest to you? I don't know if it's easy/possible to add more puzzles in a update or something,
Anyway, I'm so glad I found this - it's really well-executed and so much more convenient than fiddling with actual blocks (and a somewhat fragile booklet). I'd completely forgotten about these puzzles but, thanks to you, I can say that I'm still fiendishly good at them nearly 40 years on (dear gods, is it that long >.<)
<3