I worked on two large twin row radials in the workshops early in my career; the 14 cylinder sleeve valved Bristol Hercules and 18 cylinder P & W R2800.
Both had 3 piece crankshafts with 180 degree offset big end journals. The only major differences were, the Hercules incorporated the big end journal into the centre crankshaft section whereas the R2800 had the big end bearing journals as part of the front and rear crankshaft sections. The method of bolting the sections together, the vibration damping and main bearing arrangement was different as well.
The R4360 had, as far as I can see, a solid crankshaft with split master rod big end bearings similar to a typical car engine. There are several pictures of a cutaway R4360 on the AEHS website where the split master rod big end bolts are visible.