As long as the amount of oil paint is minimal, ie, you’ve used a paper towel to remove about 99% of it and what remains is in the textured areas, you do not need to let the paint dry and yes, you can fuse it in with a torch or heat gun. If areas of oil paint are thicker, it is best to let it dry overnite before fusing in. My general rule is to always make sure that the amount of oil paint on the surface is extremely minimal.