[spdbrake]

Definitely need to see the car and options to make any kind of guess.

A 2021 basic BDR roller starts at $47k, Coyote Gen 3 crate $9k, trans $3k, Harness, $1.8k,accessories $1k, $2k fudge factor. and your at $69.8K without tax and shipping.
Keep in mind that price is you doing all the wrenching. Add at least $4-6k to hang a motor and get it running. James Yale at Radical Roadsters just outside Houston is a dealer and and can square you away. I'd at least give him a chance to quote you.

My ruthers would be to buy an 2021 RT4 since it has a better rear end and other improvements.