Mopar didn't put shakers on 383 cars in 1970, Hemi and HP 440 cars only in 1970. They did offer them on 383, 340 and the BB and Hemi cars in 1971
My message is use what you have first, if it doesn't fit then change the parts needed
Are you running the stock 1970 exhaust system? If so does it have a H pipe between the exhaust manifolds and mufflers? If not you may be able to bolt your existing exhaust system up to the 440 motor with the same exhaust manifolds