Steve,
Here are a couple items to begin with:
1) The design of the 4 legged mast was probably std. across all 4 ships.
2) The time period you are concerned with (1956) affects the mast, not the later radars added on NEW JERSEY.
3) The photo of MISSOURI is good for the small details that would have also appeared on WISCONSIN in the 1956 time frame. I noticed a couple angled radio antenna mounts (one on each of the after legs) just above the upper height of the Mk. 13 After Main Battery Rangefinder. These would more than likely have also been part of WISCONSIN's radio suite. Also, as I mentioned earlier today, the foot rungs on the after left leg would be a great detail to incorporate, if possible, or something that the modeler may have to add with PE. I just zoomed into my original photo of NJ in 1981 (the one you showed in your first post) and it appears that NJ did not have these rungs from her 1967-68 refit - more than likely removed.
I just compared the 1956 WISCONSIN BGP with the 1950 MISSOURI BGP - you could start with the 1956 WISCY plan to get the distance of the 4 legs, since that plan shows this on Sheet 6, Superstructure Deck. The radar platform (Service Platform) would be the same on all 4 IOWAs, so I would use either of the plans for this height. In other words, the mast is common up to this point, it only differs in the type of radar shipped and the radio antenna on the individual ship.
Since you are designing for WISCONSIN, use the 1956 WISCY plan for your basic layout. I don't know how you design your 3D model, but the diameters of the legs are an important part of the design. I will do my best to try to figure out the correct diameter as no one to my knowledge has any actual fabrication drawings of this assembly. At least not nowadays. I'm just guessing, somehow 10" comes to mind, but don't take that as gospel.
I will try to find some early 1967 photos of NJ prior to her mast being altered for radio antenna use only (1968-69) - I think I may have some overhead shots of the after mast structure without the radar as she was hauled out of her mothball anchorage in Philly in 1967. If so, I'll email you scans of those photos that may be helpful. This Sunday I'll also look over all 3 BoGPs and see if there isn't some Service Platform detail that I can scale and give you a rough 2D sketch to work from.
Here is one other photo from NJ in 1968 that might give you an idea of the shape of the overall structure from above.
Attachment:
BB62 Overhead Stbd Side touched Up.jpg [ 175.43 KiB | Viewed 2975 times ]
I almost forgot - I DID do a 2D CAD drawing of the main mast - I'll have to go into it and see if it in fact IS correct and send you a .pdf of it but modified for your 1956 WISCONSIN model. Might take a few days next week depending on my work schedule. I will have to draw up the correct Service Platform, etc. but I'm more concerned with the diameters of the legs at this point.
If I can find any other info that would assist your design, I'll see that you get it.
Hope this helps,
Hank