No offense but it doesn't seem worth it. You can get a new Behr radiator from Pelican Parts for $150 and some other better fitting aftermarket ones for a little less.
Glad you got it to work. I think non-M's still don't have too many all aluminum radiator options.
2013 F30 328i - Melbourne Red
2011 E90 M3 - Monte Carlo Blue
2004 E46 M3 - Imola red