I think you are dead on. use the magnum for bittering and split the fresh hops up at 5, 0, whilrpool (or halfway through chilling) and maybe some 'dry' hops. it the equivelent of about 6 oz of dried hops.
go for all MO why skimp on the homegrown right? I would mash super hot or use a little crystal or munich maybe but that's all up to you.