That era 325 has the M-50, which has pretty much the best flowing intake manifold of any of the ITS/R BMW's. It's so good that e-36 M3's swap their stock manifold, which is the same as all the non-M's, for the M-50 piece. Still, I'd also reccomend the e-36 328 also. The extra ~300cc would just about make up for the loss of top end from the small runner manifold. Certainly, the M-52B28's 84x84mm motor has potential.
James
Hmm.. the 325's seem to be cheaper to buy, and I suppose the build cost is about the same? Is extra weight in the nose not an issue? (I'm assuming 328 motor heavier?)