Actually, in some ways it's easier to put a Hemi in than an RB motor. With the Hemi the headers come out the bottom, while the RB they come out the side necessitaiting all sorts of weird bends sparklug access annoyances. Yes, you can now make good power with an RB motor with todays heads & yes, the RB can be less finicky but it'll take more effort & more technology to get the power a Hemi naturally produces,
And if you're thinking of simply using the old fenderwell style headers to simplify the swapp you're now limiting yourself to wheel size & increasing your turning radius......