I agree that K&Ns are a good modern alternative, but opinions on them are so heated that such discussions have been banned from the e-type forum! You'll note that the ads talk about airflow, not filtration effectiveness. Paper filters do filter a little better, but only at very fine (micron-scale) particle sizes.
The originals are not remotely as effective, but you probably won't be doing much harm by keeping them if you want. This is assumes that the car will only get limited driving, and in favorable conditions. Just clean them in any mild solvent, let them dry, and re-oil with filter oil (K&N has some --). Filter oil is extra-sticky.
The old standard air cleaners (pre '60s) were the oil bath type, which did not have a replaceable element.