what sort of numbers are you aiming for?
although their outright potential is limited, you can generaly run 10's with a big block (preferably 500 inch) caddyu engine..
although they are not powerful as stock, it doesn't take much to wake them up, and they are unlikely to have had a hard life, so the bottom end generaly can be untouched - just a port job, intake manifold, hoofing great carb, cam and a set of headers - should come in well under £2000
hot rod did an article a while ago, where they bui9lt a pro street chevette, that ran 10's for $1000 with a caddy motor..