A 518 will fit an e-body without too much work as the crossmember is back further than a b-body( they need the t-bar crossmember modified). There are build threads if you google.

68 Road Runner, 69 Belvedere, 71 Challenger Vert
340 barracuda, 01 Ram CTD, 95 Ram, 04 Ram, 85 Daytona turbo Z
66 GTO, 06 Magnum RT AWD. 07 Ram CTD, 07 Ram