5.3 vortec in my 61 c10

[Bad61c10]

Hey guys I'm looking to swap the engine that's in my truck right now to a 5.3 vortec and I'm wondering if I need to buy engine mounts and what other things I will need to do the swap. I currently have a 327 and have been told that the block is the same between the 327 and the 5.3 so can anyone tell me if I need to buy new motor mounts, if so where's the best place to buy them. While I am doing this I will be putting the front crossmember from an 81 GMC Sierra. Thanks in advance!