Here's no replacement for displacement. How much power do you want? And for the heads and cam the options are endless, in my galaxie I have a comp 280 cam and that is just a little to much for my stock tranny, I have to set the idle up to about 2700rpm in nutral so I can keep it alive in drive, (I'm going to get a new tranny)
For your heads if you just want a little more power get them ported and polished. Or of you want more power than that get a nice set of aluminium heads from Summit
and most of there tech pages will give you RPM ranges for the part your looking at.