bab-91 wrote:
Do you run the risk of overheating? "The standard 325i radiator will be fine as long as it’s in perfect (i.e as new) condition." That statement doesn't fill me with confidence.

I have run my 2.7 on the radiator that came with my second E30 for about 7 years now,with no overheating issues at all.Cannot see an extra 100cc or so making that much difference.
But radiators are not expensive at around the £80/£100 mark...
Possibly more important to fit a new water pump,on both of my engine conversions I failed to take heed of this advice and needed to replace the thing very soon after commisioning the car!