Get a set of Gt40y aluminum heads if that is truely your budget. They sell New as Take-off heads for $699, and i think even less these days, and less used.
You aren't going to set the world on fire with them, but they are lighter by 50lbs. and you can get between 250-275rwhp.
They can also be resold when you get your stroker for $500+meaning you won't lose all that much.
But, me personally, after learning a lesson in buying heads, i'd just leave the heads stock until you can afford, Gt40x, rpm's, afr's or TW's.
That's just my opinion. I lost alot of money putting it into less than par parts.