go here and drop in your zip code:
Quality Discount Auto Parts | Salvage Yards | LKQ Pick Your Part
c'list, offer up, farkbook, classifieds here, swapmeets. the parts are out there, it's just a hustle to get them.
you can attach pics to the message bodies here in thread. "attach photos" or thru external link (imgur). but if you provide the PN off the heads (it's on the runner in between the valve springs) you can google that or somebody here can tell you what they are. measure the valves tho, a lot can change in 40 years.
there is an absolute TON of info here, the search function is decent if you're specific in the query but you can get better results with an enhanced google search {how to pick a cam for a 318 forabodiesonly(dot)com} will turn up excellent results.
sorry if we come off a little gruff, but we know the realities of the game and we hate to see people waste hard earned money and invest blood sweat and tears into something that's a mistake we've all made before.
i don't know how far you're into that 318, but if it's not a boat load you might be better off packing that in and trying to get a few doubloons for it and pivot over to 5.9 that would
likely be cheaper and easier to reach your 400hp goal.
i love 318's and i think they're fun builds, but if you want to make big power for cheap, you need to start with cubes and the magnum has the added benefit of great flowing heads.
that being said, a 300hp 318 in a light a-body is a blast. and that's doable on a beer budget.