Are there no radiator repair companies in the UK any more, might be a choice worth investigating! SF radiators were without question well made and reasonably inexpensive, but sadly now gone. I would explore more avenues. I found the aluminium replacement radiator in my Roadster kept the running water temp much lower/cooler than the original rad, which may effect engine management systems.
Yes, there's a firm in Wrexham I use for my Morgan rads.
Recored my Plus 4 and 4/4 rads with a high efficency core for much less than an ali rad, they've also successfully repaired some of the later Mog rads as well.
Arwyn