Dug a little deeper on sources of classic slotted mag wheels in modern sizes (ie. sizes you can actually still find quality radial road tires for). "US Mags" brand, now owned by MHT wheel, has the "U433 Indy" wheel available in custom builds; Its a forged two piece welded wheel blank drilled to your specs 8 lug x 6.5 BC, 16x8, 17x8 etc. Should be more than strong enough for even serious towing or off-roading. Problem is they cost a fortune - 16x8 = $875/ea, 17x8 = $700/ea.
As usual, no 8 lug pics to be found anywhere, but heres a 5 lugger with the larger 4.5" center bore for perspective. Nice looking wheel though..