+xSorry Steve
First, I really guess this is a commercial rim.
aramid is more resistant to abrasion, but gets a little felt-like, wich also varies with the fibre orientation, wich is a simple no go for braking surfaces.
As the pinholes are non structural you should get away with a basic epoxy. But you should really question yourself, if the rim will look nicer afterwards, after sanding of all the little resin bumps. this needs a good amount of practice to get it right. And I guess you are not planning to unspoke the rim or clear/flowcoating it? So it might very well be that the rim looks less professional finished after your (very time consuming) work
I just knew that I would be wrong. Learn something new every day is always good.