Wow this thread has taken of I'll try read this all later but in short wb our club would have no problem including your wb ute in historic rego we have a member with a wb ute much like yours .
Sure you do have mags but they are 14 inch and look period and don't look to be over wide and hanging out of the guards etc
The bull bar would also be consider period correct as even my sandman in the day had a 4post bull bar fitted when I went to Ivanhoe to visit rels at least twice a year
There is a guide on historic rego on the rms site I'll try to put a link up later got to get to work