A member on another forum brought out the article from Fana l'aviation from 1994, where is stated that the 143 was flown with a R-1830 in the nose. Supposedly being good for almost 530 km/h in 1937 on 100 oct fuel.
It is not the 100 oct fuel by itself, although 100 oct was very rare and very expensive in 1937.
The -33 engine was a two speed engine and may not have appeared until 194--41.
They did get 1200hp from the -17 single speed engine using 100 oct fuel for the P-36A but that was later. Most of the early P-36s had the -13 engine that was pretty much the same except weaker cylinders and different bearings, but used 91/93 octane for 1050hp at 2700rpm.
Just about all articles on the V-143 say there was only one airframe, modified several times and that had at least two different R-1585 engines but no mention of an R-1830 engine except for the French article?