I got one for my 66 mustang. Got one in a standard size (17inch wide) and it worked great! Didn't quite keep up when I put heads, cam and supercharger on it but I've just bought another one that's a bit bigger.
Interestingly I had an engineering friend do some flow/heat transfer tests on a cheap ebay radiator ($110) and a mishimoto radiator ($600). Both radiators transferred the same amount of heat and flowed the same. These cheap radiators are getting to be decent quality now, both radiators I got had decent aluminium (welded fine with no impurities) and the build quality was ok (not as good as PWR). My only real concern is the longevity of the cheap radiators.