None of the choices are cheap nor ideal.
5.7 is the only thing that would move a vehicle of that weight, most expensive however. Stroke the 318 mag...but in my mind it's hard spending stroker kit money on a 3.91 bore. Turbo slant... underdog complex Lol I love the slant but it will never grow 2 more cylinders or a better port. 85 lb crank flinging tiny little 3 inch pistons around, let's turbo that, great idea. lol