Just about to start my new swap

Ok so i hit a snag actually it was a deer at high speed. Long story short was supposed to play in the snow and due to crappy weather ended up hitting a deer on my 450 r ktm two surgeries later 18 months off work bit of mush head left( no helment) where the hell to start. Both cars are gutted. Challenger front end right gone,engine trans,interior our out. Rear end is in. Dart engine trans are out dash wiring old rear end is in. Ordered Hdk complete kit . First steps to take next unsure of. Those that have done this before feel free to chime in with suggestions I'll read them all in order to try to lead off with the right foot.

As a recap builder is 72 dart, donor is challenger r/t 2012 6 speed, hemidenny k member coil over conversion. Rear parts are 741 3'rd member. Brand new carrier bearings,auburn posi,mosser axels.

Original plans were for stroked 318 there out for 5.7 hemi. Have the entire challenger car, think i'm a couple weeks out for hemidenny still. Where to start first, most important land marks of the build to make sure i get right. Will my axels and posi fit in a larger third member or am i stuck with the 741.(no r and p bought yet)

Got my last cast off a week ago so finally have 2 hands back somewhat. Where should i be starting. Thanks guys for the help and advice.

Also picked up a 1950's milwaukee mod 100 4 ton lift to lift front end up and dow while trial fitting hemi and tremec.

Cheers
Mike