if you can not afford aluminum heads try finding C8VE-A, C9VE-A or D0VE-C heads They have the small combustion chamber. 2.09 Intakes and 1.65 Exhuast
OR the D0OE-R 70-71 Cobra Jet Heads. 88 cc chambers with 2.19 intakes and 1.73 exhaust
D2OE-AA, D2OE-AD or D3AE-FA They are the police intercepter heads They have larger chamber but have bigger valve. Same as the cobra jet heads but have smaller port size. but the port size is still larger then the early heads.
Make sure you rebalance the bottom end. Use a stud girble on the mains and new rod bolts. If not it can be a big mess. Been there.