Single turbo on dual exhaust

I would go single. You will spend less on turbo with one good medium size, then two smaller units, plus the associate cost of plumbing hotside, cold side, and hose for oil feed and return, etc.
Many have good success joining one side into the other with good results. The variance of one side being a little longer then the other will be minimal.
A single is also more forgiving for packaging of intercooler, etc.
Can you post your basic combo?

"Nitrous to spool, and alky to cool", seems to be a decent direction, using the alky / water injection to cool the charge, and alky has the advantage of combustability, and injected water does a great job of steam cleaning combustion chambers to minimize carbon build up which can lead to detonation.