The car that your grandfather raced was a 1937 Ford flat back sedan, the body was a US style (here in Australia we got a 4 door with a 'hump' for the boot)
Monogram released a kit of it Hotrodded with a 351 windsor(?) ford motor, although the kit has modern running gear by combining two kits (Like the 37 and the running gear from the 40 Ford) you could build a nice replica.
The 37 sedan kit I have is Monogram kit no#2757 last released in 1991, you could probably find it on e-bay.
I was going to modify it to a coupe version to build a replica of my 1:1 scale 1938 ford coup hotrod but the 37 coupe kit arrived and vetoed that idea (Too bad the 37 coupe kit is a 'business man's' body and not the 'club' coupe like my car!!)
Happy modeling!!