Having done this conversion and it working well I have decided to ditch the tape covered case and, seeing Charlie's own white cased version, take Lardo's advice re painting, it so a tin of primer and acrylic gloss white are on order.
Whilst I wanted a touch of originality I decided a bit more usability was in order hence the fitting of a switching reg, one of Karl's video boards and a "clicky" keyboard.
One aspect I wasn't too happy with was having to revert back to tape loading so I programmed another EPROM with the ZX80 ROM image plus the ZXpand drivers and so now have quick load and save, rendering tape use defunct.
One thing I mentioned in another post was that it didn't play nicely with "flicker free" displays. After burning the latest EPROM and using it with the spand I now find some flicker free stuff working, example omissions being the Metropolis demo and flicker free 1k FIDE chess.
Why this should be I cannot say but possibly a timing discrepancy of some kind.
I've enjoyed this little sojourn into zeddy modding and taking everything into consideration moneywise it's cost me a tad over £50 ,some bits were already on the ZX81 board, and for anyone who has a spare ZX81, a suitable chip to program and the other bits and bobs well worth the effort, the alternative being, for anyone wanting the ZX80 "experience" , is to buy one of those "Untested-no returns-broken case-no leads or power pack affairs that are listed usually just shy of a grand on a certain auction site.
I know which I prefer and for anyone wanting to have a go themselves, have fun!