Actually there might be clearancing for the stroker crank, but that's typical for a stroker build.
The 2 things I listed are the only additional things to building it as an rb2630, aside from the mods to make it fit, adaptor plate, slot bell housing, slot engine mounts, modify dump pipe, turbo oil drain, maybe cooler pipework.
How long a build takes depends on how much other stuff they are doing....