66 Dart trans swap question

Thank you all for replies. Learning as I go and have questions during the process. It is not to be a drag strip car but may be adding power and wanted to plan ahead. Can’t street race like the old days and am too old to be doing so. Surely a built 904 would suffice snd will probably not ever been in it long enough to achieve peak HP of the motor.

Also did not want to cut up the car…