Going with the modified magazine catch and a 10 or 5 round magazine will comply with making the rifle NOT an Assault Weapon under the California definition.
The modified magazine catch and the 10 round magazine, should render the rifle as a "Semi-auto rifle with a fixed 10 round magazine or less".
Loading the magazine through the ejection port is easily doable, but a little more time consuming than the striper clip dust cover.
You can make the stripper clip dust cover work on a FAL receiver not cut for a stripper clip cover. The stripper clip dust cover was designed to fit Inch receivers with the proper receiver cuts.
You can either modify the dust cover or the FAL (metric & some inch w/o the cuts) receiver to work. But, common sense usually dictates on modifying the cheapest component.
You can cut off the rear tabs off the stripper clip cover, so that it'll slide up flush with the rear of the FAL receiver. But, you may run into a problem of the cover sliding forward. It may slide forward if the dust cover slot (right side only) is cut through the ejection port. If it is, you can fill the dust cover slot with JB weld or something that will prevent the stripper clip cover from sliding forward.
I went the more expensive route and had Entreprise Arms CNC my FAL receivers to accept the stripper clip cover. You can probably be able to do the same with a dremel and a grinding wheel. But opted for the more professional method.
Here are some pictures of the stripper clip cover on a fixed 10 round mag FAL.
www.webshooters.org/diy_g1_stripperclip_topcover.htmShould the CA DOJ ever add the FAL series to the California assault ban. You will be able to register them as an AW at that time and revert the 10 fixed mag FAL into a regular detachable mag FAL with just the replacement of the stock "unmodified" magazine catch.
Also, nothing can stop you from going shooting outside California and replacing the modified catch with a stock catch, so that you can enjoy the FAL as it's intended.
www.entreprise.com are good guys in my book. I have several of their receivers and they are all 100% reliable. They were able to help me get my Imbel 100% working, before I knew how to work on the FAL. Albert & Lawrence (Entreprise employees) have been very cool and helpful to the WebShooters group. We've had a large group buy of their recievers and the have sponsored several of our club shoots. Check them out, if your in the neighborhood. The have a Pro Shop open for visitors. You can check out all the different models and they'll be able to answer any of your questions.