Welcome! You have discovered the dilemma most of us with old 3/4-ton trucks have faced: 2-piece, or locking-rim wheels. What to do about them? Most auto tire shops won't touch them as you learned. Most truck or ag equipment tire shops will, but it's pricey. The real problem is not that they are unsafe, when in good condition, but that they are labor intensive and a tire machine really doesn't help. Especially when they are rusty!
Some guys have found some years of Ford or Dodge 1-piece drop-center rims (16") will work and clear the tie rod ends. Others have used trailer wheels. About 21 years ago I bought a set of 1-piece chrome 8-spoke wheels in 15" 8-hole pattern. But they rubbed the tie rod ends so I added disc brake spacers.
Do a search of these forums as it has been discussed many times. I'm using the 2-piece rims on my 50 now - in fact I'm putting new tires on the front right now, at home.
Good luck - and be safe!!
