You are asking for us to design the whole thing. We can't do that. Your situation is pretty specific. Lots of us have done swaps, some radical swaps. Maybe someone has done this specific truck or near. In lieu of that, We can start you off with the procedure.
The method is to mock up the components. You can't say it will or won't work until then, The mock up procedure enables you to think of ways to make it work that you can only see with placing parts in approximate position.
The good news is you already have the components. You won't be the first guy to put a SBC into an old truck. The normal challenges you describe: space, steering, exhaust, motor mounts, trans mounts......all have solutions from the aftermarket and your fab and design skills.
Getting it to fit, safely, adding better, stronger steering and brakes, if desired, will cost time and money. Whether you will like the performance or look and feel is another story. I don't know if a LS1 is a good motor for hauling "Heavy Duty Trailers" or not.
So if you are sure it's what you want, take off the front clip and use a cherry picker, hoist, jack stands, jacks, chain, timber.....whatever, to position it all in close proximity to study the situation before cutting, drilling or buying anything. Then make some decisions, consult Stovebolt using good pics and information you discover.
If it looks too hard, expensive or will create a Frankentruck, you haven't lost anything but time and haven't ruined any components.
