I was asuming you must be either an experienced boat builder or it was a very late April Fools Joke!
What's the storey with the 1:7th scale aircraft carrier - Is the build a comission for a naval museum or something or do you have a very large front room with a very large empty glass case waiting for something to go inside? As far as plans - I'd go for purchasing the largest scale kit I could find and then making a set of plans from that - in something that scale a foot here or there won't notice too much!
Also what are your plans for modelling aircraft for the flight deck? Would be worth spending the time making moulds and then producing the parts in bulk! What was the reason for modelling the ship 1:7th it seems an odd scale - If you went for 1:6 you could use action men as crew!
You could also check out the thread on a proposed build of a 21foot HMS Hood on these very forums:
http://www.scale-models.co.uk/showth...highlight=hood I would have thought the problems you both face regarding sourcing plans and scaling up details from smaller models, reliance on images and photographic images for research, etc would both be similar for the two builds.