If the pushrods are still true I would not worry about them
Yes select the spring type you want and go with new lighweight retainers and keepers.
Also new valve stem oil seals.

Valve cover seals are reuseable so if they are not leaking you do not have to replace them

You really need to 1st choice what type of spring you want to use.
I find the dual springs that the inner springs tend to break as you can see from the photo when I changed mine.

The springs used for the L92 ( shown on right) seem to be a good swap and are the beehive type that use a smaller and even lighter retainer.

With a supercharger and as old as the stock engine is I would not go with higher lift rockers.