Getting ready to swap a 5.7 into my 73 Dart Swinger

Well folks i would hate to tear it all down after all this work but is there a relearn for timing i believe my car is pulling -64 degrees timing...
When the car runs every seems fine! Still only ran once just taking the time to look over some data i logged during crank missed the log when it actually started.
Also have the axle off my mustang 8.8 should fit with little to no mods at all just new perches and u bolts.
Hp tuners might be a little too advanced for me!!!
Trying to get any tune or tuner and see if its just the mods...