Assuming that forged cranks will became available for rover/sbb V8's, Windsor has 3" mains available. Buick used 3" and 3.25" mains to cut cost, using much cheaper cast cranks. One problem with this is bearing speed, not good. Sounds like bearing spacers might work, to use 2.5" journals on 340/350 sbbs. While we're at it, why not rotate them in the housing bores approx. 5 deg ? Obviously the oil feed holes will need to allow for this. Why do such a thing ? This crates an overlap that should reduce side to side movement. Note, you do not rotate enough to inhibit installation of the bearing halves. Science, roverman.