What head should I get for a 318

Well I been looking to upgrade my heads this coming spring cause theres not much else I can do to get more power I believe. First heres what I got -a 1979 318 over .030 with headers, a offy equal flow intake manifold, a holley hp 750 carb, msd 7al box with matching coil and 3.91 gears with a 904 trans with the low ratio gears and a manual valve body. It runs just fine but I want more and yeah a 360 or 440 would be best but $$ can't do it.

Can not decide if I want to just take my 1979 heads and put in 1.88 and 1.6 valves and mill .030 off-it has 8.5 pistons. Or should I try to find some 1970 318 heads and do the bigger valves and cut. Or what about those late 80's 302 heads, should I try to find those and drop the big 1.88 and 1.6 valve. Was leaning towards the 302 heads but hear they crack easy and I hate to have that happen to me during the summer after I spent $$ on them. I look at Indy heads-Aero racing site and they have 1980 67cc-70cc 318 heads with the 1.88 and 1.6 valves with all new valves, springs and guilds for $399 or 360 heads for $499. But I hear the big ports are not good for a street 318 motor. They can put harden seats in for $80 and blow blend the ports for $150. They mill both sides the bottom and intake for $175. What do you think I should do ?

I have adjustable rockers so I am thinking of Comps 270 mech. cam also, I have their 268 HY right now but its coming out .

Mangum heads are out, I have too many nice smal port intakes and my adjustable rocker arms so please I know they might be the best but do not want those