The physical swap is pure bolt in... super easy.
I don't know about your current tranny though.
It will bolt right up and not know the difference between your 5.0 and the 351.
BUT: Your 2 engines may have a difference in balance, depending on years... 28oz vs 50 oz.
Also, even though the 351 will bolt up like a 302, the tranny may not be able to handle the torque of the larger engine... again, depending on exactly which tranny you have and the condition.
Other than the tranny, it is a very straight forward swap.
The 351w is exactly as a 289/302, just a little taller.
99% of the external accessories are a direct swap.
Some notable exceptions are:
Oil pan
Distributor
Intake
That's all I can think of now.
The exhaust will be tighter to the shock towers, so your need for different manifolds/headers is kinda hit and miss. Try what you got, then if need be, there are lots of swap options.
Good luck
Dave