manifold is by Ziotti (from memory - not at home right now)
The one above in this post on eBay seems pretty steep to me. But very cool.
Those filters remind me of one of my first vehicles. I was 13 or 14 y.o. and bought a Triumph TR4 Surrey Top (my first and last British car). Even though the car was only a few years old at that time, they were already very cheap to buy used. I did a lot of 'custom' touches to it, including a set of aftermarket air cleaners for the twin SU side-drafts. The filters were very thin 'pancakes' that likely flowed less than the stock filter box, but that's what was available at that time.Seems like those air cleaners would be awfully restrictive