looking into possibly changing the heads...which ones???

i know nothing about heads...or anything that should be changed during the process but everyone says with all the bolt ons i have this would be the next step. which heads should i choose? here is everything i know is on the car,

gt40 upper/lower
f303
bbk 70mm throttle body
bbk 70mm maf
bbk cai (fendermount)
bbk fuel pressure regulator
underdrive pulleys
bbk headers
borlas w/dumps not sure of x-h pipe
3:73s
short shifter
200a alternator
optima red top

and it has just plain gray valve covers on it right now? thats all i know thats on the car b/c all engine work was done b4 i bought the car. and i didn't get a "build sheet" of all aftermarket work performed.

going to be doing my 5lug swap/cobra brake install next month than ill be looking into doing some engine work.

this is just my hobby/fun car...want it to be streetable...dont want much more than 350-400 horse...just an all around good/fun streetcar. i just know nothing about heads...rocker arms etc so figured i would ask the experts...thanks