Well, I don't know that the airplane would be a kit airplane. Most of the speed models were so simple that all you needed was a pan. There were a couple of pans available but I think only one was widely available and that was because it was used on rat racers. The pan in the picture is that size.

If you look closely, the model shows two leadouts and they come out of the right wing. That model would fly clockwise, something a lot of speed guys did. There are two leadouts so the airplane obviously wasn't one of the monoline, no expense spared models. It also looks like there are two elevator halves, another suggestion that it's a somewhat early speed "design".

The dolly looks to be decently constructed. The tires look so clean and shiny, I'd bet they hadn't rolled a single takeoff.

The cars in the background are definitely pre-50's. More exactly, they're models that were made before 1950. Can't tell the make. A lot of them back then looked very much alike and the difference by year wasn't significant. There weren't many made in the late 40s because of the war and those actually look like they could be pre-war.

It's hard to tell what class the model would be since the middle classes were very little different in size. Since the engine's mounting lugs aren't showing on the sides, through the fuselage, I'd guess that the engine was definitely not a 60. I'd bet it'd be a 40 or 45. We often filed the lugs to blend with the sides of the pan on the larger engines. The pans often had shelves inside for the smaller engines' lugs to sit on. You'd grind that out for the larger engines and then the lugs would stick out. You'd file them flush with the outside of the pan and build the fuselage around them. And you'd see them on the larger engines.

The coat he's wearing was made of a "modern" fabric for the time. It almost dates the picture into the 50s. And that's possible.

But unfortunately, I don't know any real specifics about the airplane or engine. Sorry, but most of the speed jobs were made sorta from scratch. You'd get a pan and spinner and go from there.