Yes, it sounds so innocent doesn't it?
That dreaded knock knock knock, or tap tap tap of a rod bearing.
My car Club mates say that with ongoing motorsports involvement it'll happen - sooner or later.
I feel your pain mate, as I've just been through it.
In hindsight I would likely install a JDM low-mileage equivalent instead, to reduce the time without wheels, but either way expect it to be considerable.
Best is to keep reminding yourself that the end result will be worth it, as the motor will be better then new and worthwhile to work towards.
Options I am aware of are:
1. OEM rebuild,
2. Performance rebuild, i.e. built motor,
3. JDM low mileage motor replacement, and
4. OEM replacement.
Expect to be down for a month. I chose option 2. and it took 2 months.