As said above,
Some will blast with the engine complete
Vapour blast on its own will not remove corrosion.it’s not an aggressive procedure.
However,it will certainly lift an oil seal.
You’ve already stated that the motor will be stripped.
The 1st process is dry blasting ,prior to blasting the item needs to be degreased and free from any sticky deposits,as the blast media will stick ,effectively masking tricky bits (between fins etc)
I use a medium grade aluminium oxide.
This will damage bearing surfaces,cylinder bores etc so these need to be protected.
Only once the item is completely free from corrosion etc it can be vapour or wet blasted.
If you think of the wet blaster as a big bath tap.
Through the tap is water and glass bead,in a slurry.
This is pumped at high volume,
Added to the slurry is compressed air at a huge volume.
The glass bead,being lubricated by the water peins the surface so it’s sealed and doesn’t attract dirt.
On a sand cast component,like bmw,guzzi etc,no further treatment will be needed.
On jap stuff,being die cast,there is more zinc in the alloy to allow it to flow.
This will start to corrode pretty quick so will need some kind of protection.
As to cleaning,,,,,,
Jap castings are complex with blind drilling’s etc etc.
Steam clean,
Compressed air
Paraffin tank
Repeat until happy.
You could use a ultrasonic cleaner but be realistic about their limitations,
If something is sat horizontally any dirt just vibrates,so a gallery full of media will still be full of media.
Hope this helps
Edit,
Don’t clean the blasted item with any trace of alkaline,
As you will be paying to get it done again.