Dave,
With respect, I do not believe that there were any design or production holdups that explain the late release of the V8 engine for commercial vehicles and big trucks. After all, the only difference between a '32 passenger car chassis and a commercial vehicle chassis is the number of leaves in the rear spring and that difference is the same, four or V8. Further, the V8 engine was released for station wagons two months after Job #1.
Rather, the late release for the other commercial vehicles and big trucks more likely was a function of the large inventory of B engines produced before the decision was made to proceed with the production of the V8 engine and to not build four-cylinder vehicles until V8 engine production could support V8 vehicle production. As a result, nearly 50,000 Model B engine/transmission assemblies had been produced before the first one was installed in a vehicle chasis.
From Ford's worldwide production records, 3,894 '32 commercial vehicles were produced with V8 engines and 3,682 '32 V8 big trucks as well.