I've done several of these swaps. In fact, I've got one sitting in the garage mid-project right now. I've done the WC1200 as well. Both can be done without cutting the bulkhead.
Where to begin though?
Here's my BEST advice to a guy with little to no fab skills.... Either do one of two things, buy the stuff you need to do a factory swap. i.e. buy the hoop, post and factory straps. BUT, honestly, if you got the straps and the 1.5" spacers... look for a NON valved motor! You can have the motor on factory straps and fit a non valved big block into the chassis. The valves are what interfere with the post and hoop.
If you use a PA plate, your gonna have to cut the bulkhead a little bit for the engine case, and then cut out the cross beam brace to make room for the water pump housing. The PA plate mounts the motor far enough to the left to clear the steering post and low enough to clear the hoop. So again, cut the cross beam and notch the bulkhead. Then buy the straight carb mounting flanges so the carbs clear the jackshaft.
If you have a little skill, my preferred method is use stock straps, torque plate and 1" spacers, then shim motor mounts to fit the correct c to c of clutches. Then cut the hoop and weld in a bent hoop section, and modify the post(or find one cheap). Then the carb situation is easy with filters and you don't have to cut the bulkhead at all.