The big ends are held on with flanged nuts, I think these are squashed for locking on the thread and don't normally need changing unless you do the studs on the con rod too. You only need to replace stretch bolts for peice of mind, as all other bolts/nuts are only torqued up there is no need to replace these unless an area of damage is visible on the bolt. It would be advisable though that new 6mm bolts be fitted to the sump pan with a new gasket as the old gasket is pre compressed when tightening the bolts it would be more likely for a thread to strip, especially on the rear crank seal housing as this is just alloy compared to the cast block. I only say don't bother for some bolts due to the cost you could incure.
Hope it goes well, don't forget to apply a light smear of oil on the threads of any bolts before fitting, this aids with the torque accuracy.!!
