[1968 nova ss]

hey guys recently got my other 68 nova ss 396 going.. problem I am having is the driveshaft front yoke area probably has only a quarter inch clearance at tunnel area. the 68 frame was beat up a little bit so I have a 69 nova front clip underneath now.i have installed 68 big block frame mounts and motor mounts..will I need to install 69 frame mounts and motor mounts ..to get proper clearance at driveshaft area..? will that make up the difference to get an inch so clearance at driveshaft ?or , do they make a tranny mount shorter that the standard 1 3/4 tranny mount.. any help appreciated. Chris Teed.