OK, so I've followed the advice and checked both places in the engine bay for the VIN - nothing at all
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Also, totally stupid as it sounds, I can't find the small VIN plate that I could've sworn was in there.
Photo of where a stamped VIN
should be in an Early Bay;
http://rs1293.pbsrc.com/albums/b586/small_purple_cat13/001_zpsfff284ec.jpg~c200" onclick="window.open(this.href);return false;
I also checked out the hinges of the engine compartment and they
are Early as far as I can tell;
http://rs1293.pbsrc.com/albums/b586/small_purple_cat13/003_zps65a92049.jpg~c200" onclick="window.open(this.href);return false;
The rear bumper is certainly not an original fitting - those brackets look bodged to me;
http://rs1293.pbsrc.com/albums/b586/small_purple_cat13/004_zpsa32afe2c.jpg~c200" onclick="window.open(this.href);return false;
Also, if it helps, I've got disc brakes front and drum brakes rear and the front of the chassis looks like an Early to me (I'm going off the pictures in the Haynes Manual and the diagrams and pictures in both the VW Heritage and Just Kampers catalogues here).
Make of that what you will. I'm unsure whether to proceed any further with this now or strip the thing completely and sell the bits.