Hey man,
Cool you are looking into Twenties! As for lots of info (including some very handy dandy and cheap Bracket and Fork choices & explanation) as well as lots of pics (b4 and after) of my conversion chk:
http://www.rhizomes.nl/twenty.html
And do a Search for the recent other Twenty thread, some pics and lots of great info
there too. Plus follow all the links you encounter on the above.
I'd be curious to hear what you think about my Twenty!
Also i thought it might be good to stress that if you want a Twenty frame to make a "Super light" bike.. well it is prob. not going to happen! The frame is a tad heavy hence your bike will never be ultra light. I know because i have replaced every original part on my Twenty by mostly quite light ones and few parts at that. Mine is not heavy but not super light like some other newer folders. If however you want a frame that gives a great ride, could last you decades (Steel = good) and take a lot of abuse, the Twenty is just the thing.
Good luck! And make sure to post your experiences & pics please!
PS The pics you posted are very nice but neither are Raleigh Twenties i think (or did you mean they are both Twenty inch or...?)