Probably a lot better choices for heads then 305 heads, even a set of Vortec heads would be a huge improvement...

How about keeping the 350 block and innards, then selling or swapping the rest of the small block parts you have and come up with a decent pair of heads??? As for the old cam--probably not a good idea in a fresh engine... Budget is one thing, but don't cut yourself so short that you end up with an engine that won't last......