does it have the driver side 360 engine bracket and is it bolted to the right side of the ears/lugs on the block?

are you sure the pass side engine bracket is on the right side of the ears/lugs on the block?

340/360 use a different driver side engine bracket than a 318,but should have been on the 408/360 based block to start.

the 318 bracket will need shimed with spacers

make sure the trans mount has not slid on the bolts/holes or in a bind.