as others have stated your current motor location is too low
you need the cross member to support the spring perches up from bowing the frame in
these trucks came with factory sbc v8 motors and retained the x-member
though there was a bracket riveted on the x-member
my truk originally had mounts similar to what warrior posted
i made this type mounts to go to side mounts and used 68 chevy truck mounts
these are easy to fabricate; a couple triangles and some 3/8 tube
as i recall the tube should be level or a little above the top of the frame
