Since that year also came with the 390, you can just use original mounts for the motor. From what I have heard on the C6 swap, you will need to modify your tranny cross member. Every thing else should just be a bolt in deal. Maybe some of the other members that have done the C6 swap will chime in and let you know what needs to be done to the cross member.
I can help you on a C6 swap. If you had a cruise-o-matic installed earlier you can use the same transmission mount just like it was. But, you'll find out that the crossmember is farther back. It's far enough back that the front holes on the ends of the crossmember lines up with the back mount holes at the frame. Sooooo, make a plate out of 3/16" or 1/4" to fit between the crossmember and the crossmember mount on the frame. You'll make it long enough to capture the front mount holes on the frame the back mount holes on the frame also it'll be long enough to capture the back mount holes on the crossmember. You can also make this out of wide angle iron for extra strength. It's easy to do and your crossmember is not going anywhere when you're done. Jim PS You'll have to change the yoke on the driveshaft to match the C6. That's it.
You will need all the front accessories for the engine, alternator/genorator, p/s pump, and all the brackets for the 390. 63 390 front motor mounts will bolt to the frame and engine, for the C-6 the crossmember needs to be moved back about 3". You will need to change the front yoke on the drive shaft for a C-6 one otherwise the driveshaft is ok. You will need to change the throttle linkage on the firewall too. Oh, and you will need a 60-63 352-390 radiator and surge tank. Not sure if you have a XL or 500 but if it's a 500 you will need to change the shift linkage from the frame to the engine (Z-bar) if it's an XL then you will have to fab linkage for the floor shift to the C-6.