100% standard bottom end is fine, but use ARP rod bolts, and stud nut kit, oh and ARP flywheel bolts.
Keep the CR std, people that can map properly can map greys, but these are no longer made, so that has to be a consideration if one goes duff ?
Whilst apart it would be wise to have the pistons pocketed, I would get the super heavy 4wd flywheel lightened as well, some mild head porting would also pay, but depends on budget, and what work is needed once engine is apart.
Does it defo need a rebuild ?.
As for ecu, I would use a aftermarket one, that doesn't tie you in to having to use a certain few people that can deal with the w/m std ecu's, that way you have a lot more choice.
Don't pay just for a name, choose who you want to map it and ask them, they will have a preference, as most will for a certain one, though a lot just go for a certain make as someone else is using it!!
The V4 is well worth looking at, amazing cost wise for what you get.
tabetha