Classic & Vintage - Raleigh Supersport Bottom Bracket & Crank

Hello

this is my first post on this site and i'm new to bike rebuilding and in need of some help:

I am wishing to rebuild my brothers old steel framed Raleigh Supersport from circa 1989. It has square tapered bottom bracket measuring 144 mm (122mm from end of squares, 144mm including the threaded bolts at the end. The crank is missing so i need to get a new one. Can anyone tell me what will fit and what to get?

also, I cannot remove the crank side threaded cup despite soaking in wd40 over night and putting in a vice and knocking with a big hammer and shaped peice of steel. i realised it is a left handed thread but still no joy. i'm wandering wheether there is any need to remove it as the rest of the bottom branket assembly has been removed and fully de-greased and there is no way it will come out with use.

i'm wanting to build a nice road bike at not much cost for commuting in London as i'm fed up of getting beaten by road bikes when i'm on my hybrid!!

your help on getting a crank that will fit will be greatly appreciated.

Your new best friend, Sheldon Brown has a great tool for getting those cups out and it only costs a couple of quid.
http://sheldonbrown.com/tooltips/bbcups.html
Before you do that, though, look at it really good with a flashlight (or torch) and if it looks good, you don't need to monkey with it. just clean it and grease it where it is and ride it.
I think most any cotterless crank will work for you with the exception of some early French ones.

They don't call 'em fixed cups for nothing. :) The upside of English and Swiss left-threaded fixed cups is that they rarely come loose while you ride. The downside is that they can get very tight in the frame.