Flight Helmet: Unidentified leather flight helmet (so far very difficult to identify). It has leather-covered ear caps with 3 grommets in each cap.
Goggles: British Royal Air Force Mark IVB with flip sun shield. Fairly rare, and probably quite expensive these days. May be worth your time to create a replica out of the more common British-style aviator goggles (the type used by Toecutter).
Search eBay for RAF MarkIV goggles
Long brown leather coat. Raglan sleeves, double-breasted, with removable belt. Comes down above the knees. No epaulets. On his left chest, he wears a yellow fabric flower brooch.
Long, narrow, knit, lavender scarf. Appears to be cotton.
Heavily stained yellow long johns, with a button-up neck. I am assuming they are a one-piece, but there’s no way to know for sure. A one-piece is also known as a union suit. Either way, I haven’t found a source for anything similar.
What you can do instead is buy a set of 100% cotton long johns and dye them with a couple packets of yellow dye, as they apparently did for the film.
Pink “Chuck Taylor” Converse All-Stars low-tops. Check them out on Amazon.
Unidentified brown fabric-covered groin protector. It could have been custom-made as a nod to the droogs in the film A Clockwork Orange.
Long spyglass telescope. Manufactured by Broadhurst and Clarkson (London). Appears to be at least 3 feet long and is made of 6 sections. Looks like antiqued brass.
Search eBay for brass telescopes