Pro Street Look (18" fat tire) without cutting frame?

[66chevy43]

Need help from the C10 gurus! I want to give my truck the pro street look without the pro street cost. Is it possible to install 15x14 weld wheels with 29x18x15 Mickey Thompson sportsman radials on a stock frame? I'm rebuilding my rear differential and will narrow it to accommodate the wheels with recommended backspacing, also going to take out the rear springs and install coilover shocks inside of frame rails and replace my stock trailing arms with tubular arms. Is this a possible to do without cutting stock frame or should I just install a new rear clip?

I done some searching and read someone has done up to 15" wide tires with stock frame, but no 18" wide meats! I measured under the truck from fender lip to frame and have over 18.5+ inches and can always roll the finder lip to increase distance if need be.

I've always like the looks of the pro street since I was kid and just want to install the wide rear wheels with fat tires. She is being used cruise around once in while, not drag racing. I think I spend more 90% of my time working on than actual driving it. She is a 1966 C10 fleetside, 12bolt limited slip rear diff with 285/40R-20 tires and 10 wide wheels.

If anyone has done this operation or came close, can you please post a picture with specs?

Thank you.