will a 383 squeeze in a 73 duster?

yep and if u use the c-body mainfolds they will have to milled about 5/16 to work with power steering.or headers will have to notch the k-member for oil pump clearance.u may have modify the transmission crossmember. the hp mainfold means the high performance ones.will just have to get your driveshaft cut down some. read that article above u can also check out bigblockdart.com go under the tech section.