New radiator for 240

[peterdpps]

The radiator in my 240 is at least 32 years old and was recored about 20 years ago when I had aircon fitted. Since then it has run well on an electric fan but has recently started to get hotter than usual at 80-90 on the temperature gauge. Flushing has improved it slightly but my mechanic says the core seems about thirty percent blocked. On that basis I’ve decided to splash out on a new radiator.
I’ve had quotes from NAR for either a brass and copper version or aluminium type both produced on original pressing.

Question is which version would members suggest is the most efficient?

Thanks in advance