Right okay guys just a follow up from above;
Many thanks to all those that have chimed in with the help. Very much appreciated guys.
I decided that the easiest way forwards would be Chu's brilliantly simply and effective idea to just re-rivet the mounts on the bottom on the rad where they should of been in the first place......
Unfortunately things are never that easy, and the mounts on the Nissen radiator seem to be either spot welded in place of held in place by some super-duper special glue. I tried drilling and enlarging mounting holes, chipped at it slowly with a chisel by they just simply won't budge. I gave up as aluminium being such as soft and malleable metal, it doesn't take much to twist and distort it.
Essentially what I ended up doing was cutting them off and using the ones from my old radiator as they WERE riveted on in place so much easier to remove and relocate. Luckily I had kept my old radiator and hadn't thrown it out yet so I still had them to repair the new Nissens one.
As I had to remove the radiator, I thought I'd take a photo of the obvious MANUFACTURING DEFAULT of the brand new Nissens rad vs old one:
So I ended up cutting and grinding the new nissens shroud mounts completely as they had to be removed in order to successfully fit the OEM cooling fan shroud.
I'm still a little pee'd that I had to do this as essentially waste my time and effort having to correct someone else's cock up, despite it being a brand new out of the box radiator. Luckily all went back together successfully and back to how it should be.
What's even more annoying is the fact that my defective nissens radiator can't be the only one floating about out there. It's not like Nissens built this specially for me. There must be loads of them out them and it must be I known problem with that particular batch. I took a closer look at the radiator and sure enough it's got a date and batch code sticker. If the Nissens UK representative hadn't of been such a complete and utter tosser, he would of simply asked me for those numbers, relayed it with Nissen HQ in Denmark and they would of been more than likely aware of this faulty batch and corrected the problem ASAP without me having to prat about correcting THEIR mistake or even having to fart about with the supplier in order to wait (weeks/months?) in sending my one back, then confirming there is indeed a problem and then eventually sending me out one that actually fits properly.
Long story short its sorted now. But thanks to ignorance and incompetence of the Nissens UK after sales representative, I was forced to modify and D.I.Y a brand new out of the box radiator and waste my spare time making it fit properly. This matter SHOULD of been easily and promptly dealt with. No excuses from Nissens. Everyone makes mistakes but its the way you got about correcting them that makes the difference in this world.
I will now think twice next time ordering a supposedly "quality after market replacement" from the likes of Nissens and also ordering goods online. Thoroughly disappointed with Nissens after sales and it will more than likely be the last radiator I will ever purchase from them. Not a happy customer and let hope it doesn't spring a leak anytime soon..... I've driven with the new setup and all seems to be well for the minute with no further apparent defects.
Thanks again to all those chimed into this thread with helpful suggestions, again I thank you all for help in this issue. Special shout out goes to @Chu for simply relocating the mounts idea. Thanks mate, I owe you a beer for that one