I owned a pair for years that I got for $100. I thought they sounded lifeless as compared to some other vintage speakers in their price range- sorry, no offense intended. I would seriously think about spending that much on a pair of L 100. Depending upon their condition, their max value in great shape isn't much more than $1000 US. You'd never get your money back out of them. I'd sell them, add the $600 and get another speaker. You can buy a lot of vintage speaker for $1k-1.5k.
OTOH, if you are looking to experiment by building your own, and you think that you may reuse the parts, that might be different. Might is the operative word here...
OTOH, if you are looking to experiment by building your own, and you think that you may reuse the parts, that might be different. Might is the operative word here...