I bought an Alloy Series 3 radiator from eBay for my Lightweight . Fitting wise is identical to the blocked series 3 Radiator I took out . Its a quality item.
No longer need it as I'm converting to Electric
On both series 2 & 3 the radiator sits behind and below the crossmember, not on top of it .
On the Holden conversions a L piece usually gets cut from the crossmember , inverted and welded back to allow original radiator - theres your problem

