101 Sqn Merlin engine in car!
RS30, sorry to disappoint you, but you haven't found the car you're looking for. This other car does exist and looks a peach, but is a "modern" custom. I'll explain..
RB, who I've been a casual acquaintance of for years has been building it for, must be, nearly twenty years. I was motoring past his place tonight just as he was unloading it from a trailor after a show. I stopped and said hello. It now has a silver arrow appearance body on it, which has been his dream for many years. Made by an old craftsman who used to bend metal for Coopers, I think. It actually has a Hurricane engine in it. A fact recently unearthed by Rolls Royce. The Merlin came out of the 'plane in 1941 and was put in a tank. From there ending up in the car. The chassis is indeed vintage, which I suppose is why it flexes! Knowing what a perfectionist RB is, I'm sure he would have beefed it up a bit. I usually have a camera on me but didn't this evening, but as he's showing it again in two weeks, I could photograph it then. It was running a bit rich on four triple-choke downdraft Lambo carbs. Years ago he told me it had a two speed dragster gearbox.
Testing has taken place at Brooklands and Duxford and this revealed a lack of brakes, soon to be modified. Among other things, RB intends to hill climb it, probably at Shelsley Walsh. One (very) old boy who saw it said he remembered watching it race on the banking at Booklands, RB let him keep his fond memories.
So, it's not a genuine re-engined 1930 competition roadster, but does look it.
Good luck with your search.