Alright...way to dive in headfirst XD.
Since you have a scope, you could tell whats in the cylinders, so, use compressed air, and vacuum to evacuate the cylinders, and make sure nothing is in there.
OR, if you're deadset on pulling the heads, then do so, to make 100% absolute sure there are no foreign contaminants in there.
The VS cam is very streetable, but often overlooked because people want a more aggressive cam. Plus you could always run a set of higher ratio rockers in combination with the VS cam for more lift.
And yes, the modded retainers are designed for more clearance, but are usually used on an XP build with stock heads, for the required clearance.
Having the heads reworked is one of the most beneficial things that can be done to a car, but you need someone with experience, and is typically done when going for an all out build.
For a VS cam, you'd be good with a set of 90# springs, no need for anything else if you're keeping the heads on the car.
If you're yanking them off, then minds well rebuild the head, with new springs,locks, retainers, and seals.