360 414 build heads????????????

Determine exactly what you want from it and go from there.
If you want a maximum effort , the six pack will have to go.
If you want a stout street / strip piece , it will work nicely and have the show and tell factor.
W-5's are such a crap shoot and not cheap to put together the complete top end..........none of the W series heads are.......but if you find solid castings and have them done by a quality shop , you will make all the power a stock block wants to see. Again , more cam would really make it come to life.
The cam you list would probably work well with a six pack application.....I don't think you'd benefit from too much more stick in there.
Are you going to sonic test the block that is clearanced ? Not a bad idea if it hasn't already been done.