Rob - Getting rid of the MWs while keeping the F-68 axle is hard because it has 14" drums that most 16" wheels won't clear. The most common option is to swap in a Dana 60 from a '67 to '72 F-250. There's likely a mod needed to the drive shaft, and e-brake linkage, but it's said to be easy. These have 12" drums which a 16" wheel will fit.
If you want to use stock hub caps you'll have three options. First is the stock F-2 wheels used from 48 into the 60s. They have the inside nubs like your WMs. A 2nd option is to find 17.5s that were on F-250s from 56 until 66 IIRC. Third option is to have your centers pulled and remounted in new 17" rims. Stockton Wheel in CA does this and they look nice. I'll link an old thread that goes through various subjects, but gives good info on wheels. Hope this helps. If anything needs explanation please say. Stu
https://www.ford-trucks.com/forums/8...9-ford-f3.html