Welcome to the forum Jason!
Where do you want to start?
This is pretty much an open book. If it was ME id get a donor engine and transmission and getting that mocked up in the shell first.
Leaving plenty of room for all your ancillaries.
You may no doubt need to make some cuts in the bulkhead to get things to fit perfect, not sure what your fabricating skills are like.
You can update the suspension and stuff after.
Dunno if you have a live axle or independent suspension on the back. But this may have an effect on how the engine and box is mounted.
Ive got mine completely horizontal in my current project but Ive done Chevys and Mk1 escorts where the gearbox points downhill slightly as it makes for a better angle on the prop shaft if your running a live axle where the diff is constantly moving up and down with the suspension.
That said, Id 4-link the rear end with a panhard rod and have the nose of the diff pointing up 7 degrees and have unequal length links, shorter at the top so the diff levels out when it travels up.
Take a peek at Boosted Westfield rotary car on this forum, he runs a live axle on his. Mine is the Rotus project on here, you may get some ideas.
Best to ask questions on something specific, there are many helpful people on here to give opinions and ideas.