Roy: I agree with almost everything you wrote on this post (I'm having a problem with driving a front engine rail being better than sex tho').
I've personally talked to Fred Frienke about W's and Z-11's, he was a main player (working under Vince Piggins). Fred worked on the passenger car side of the performance group (as opposed to the Corvette group).
The "truck" label was slapped on the W because it was designed by a "new guy", an "interloper", a know-it-all Hungarian "hot Rodder". Many in Chevrolet engineering couldn't handle it. Looooong story, the W was designed as a PASSENGER car engine from the start, with 2% planned for trucks. It wasn't DESIGNED as a truck engine, planned as a truck engine, or used as a truck engine from 1958 to 1961 (4% of production during those years were truck engines).
The W series was planned from a W-1 (307) to W-8 (454), in other words there were 8 cubic inch combo's, one was the 348 (W-3) and one the 409 (W-6). The 409 was released early because Ford released the 390 at the start of the 1961 model year, it was PLANNED to be released for the 1962 model year (when the 327 replaced the 348).
I should write a book. Don't debate me, I have some of the pre-production planning records, and the production numbers for all big blocks ever built (all were at Tonawanda). Sure would be P poor planning if you only put 4% of your "truck' engines into trucks.
PS: the Hungarian "hot rodder' designed the ArDun heads for the Ford flathead, Zora ARkus DUNtov (he patterned it after a Mercedes diesel engine, again long story). The W block engine, 74 degree head bank angle.