It is possible to take a vanilla O1v96 up to VCM level, but it will cost more than just buying a VCM outright.
I bought a VCM earlier this year and I had looked into the vanilla vs VCM arguement and came to the conclusion that shelling out £1000 on a secondhand vanilla only to have to pay £400 each for the two upgrade packs to get to VCM level was a false economy.
Especially when I was able to find a B stock VCM for under £1600.
If you can, save your pennies for a VCM. The reverbs are worth it on their own (REV-X engine from the SPX1000, iirc). The reverbs on the vanilla are pants by comparison.