Maybe I can help. Les Schwab tire centers are a basic tire store like Discount or any other that deals in just tires and rims. I ordered custom drilled 16" Centerline Billet Champs through Les Schwab for my 63 Ranchero. Centerline Wheels, specifically the Billet wheels, can be drilled to meet the 4 on 4.5 and any backspacing you like. Example 3.5" or 4" backspacing. It took 2 weeks to order and cost me $200 each. Weld Racing Wheels also stocks a couple to fit like the Weld Draglite and Rodlite, again around $200. Summit handles the Weld line I believe.
I ran the 55 series tires and total profile height was near the same as stock.
Others on this site say the MG or Nissan bolt on wheels will fit, but I believe they only come in 13" wheels.
Gary