Lots of Impalas
According to the charts linked to this site, there were some 177,969 2 door Sport Coupes made in 1961, and most were Impalas. It's possible many were 6 cylinder cars, or 283 builds. Not many were 348s and even fewer had the top rated 350 horse 348 with solid lifters and tripower, backed by a four speed.
There were some 10,xxx Belair Sport Coupes perhaps (I have that number somewhere) made that same year. A 350 horse "W" in one of those would be pretty special
.
I'm not even sure we can estimate how many 350 horse "FH" stamped engines were originally made, but I bet a lot of them went into the Impala. I suspect a few were in the born-to-race Biscaynes and Belairs as well...
I've got a 1961 "FA" (tripower with the 280 horse heads) and a 1961 "FH" engine, one freshly built, one mostly complete. I consider them to be very rare, but not all that collectible when compared to the 409. Since I like the 1961 body style, it seems right to have a 1961 vintage "W" engine
.
Cheers!
TomK