I'd be guessing/assuming, there'd be as many modifications as there were troopies. If you look at any parade, every one of 'em shapes their beret differently. It'd be the same with a guy's jacket.
The Denison Smock was issued to guys who thought jumping out of a perfectly good aircraft that wasn't on fire wasn't unusual.
Try these guys. No idea what "Size 8" means. That's a girlie thing here. There was a U.S. site, horrendously expensive, that mentioned 3XL. And a place selling patterns.
Denison Smocks