Fan size question - Carrera 6

I am building a 2.0L Carrera 6 engine and I have found most original parts by now. Although I will not know for sure until the engine hits the dyno, it is likely to become the typical high rev's engine, with around 210 hp @ 6000 rpm.

I am wondering what to do with the fan and can do with some advise. The 906 engine used a 225mm fan which was said to lead to an optimised engine temperature and limited air resistance in the engine from the fan. Apparently, because of the high rev's, the engine could do with less cooling and hence a smaller/lighter fan. I am not too sure about the arguments because the thermostat should regulate the amount of cooling for the engine. The 245mm therefore cannot provide too much cooling, the 225mm maybe not enough, right ?

Does anyone have any experience with this, and/or played with these two sizes of fan ?

I have my eye on an original magnesium 906 fan - what would be 'the going price' for this ?

Thanks for your help !

Another (cheaper) option would be the '78/'79 3.0SC 226mm diameter fan.