Denny,
The Rochester for a hydra-matic truck had an automatic choke with a heat tube and "cover" over the exhaust manifold. I think I have some pictures if they would help you out.
I am not completely sure about a different master cylinder. I think there may be a difference in the end fitting but the biggest difference was in the brake line routing. The H-M routed farther back so it did not cross under the transmission so that the trans could be reoved from under the truck without the brake lines being in the way.
You know Tim is probably the best source of factory info you will find. The starter button color question will come up later. Obsolete Chev insisted that a cream colored button was correct. Others say chrome (in 54 55 1st) Personally, I went with black knowing it was incorrect but I felt it to be the best match to all of the other black knobs.
I found a thread on classicparts.com about a 54 H-M driveline "up for grabs" I don't know what all would be available but it is a lead for you if you want it. Also Cletis called me yesterday with a H-M trans for sale with an open driveshaft tailhousing. I don't know if anything else was available but again, it is a lead if you choose to follow it up.
