Hey Will. Good to hear from you again. Really depends on what is wrong with engine and trans now and what you are after, stock or modified. 253 with 4 barrel is nice. These days I would do hardened valve seats in head to run umleaded (without having to worry about additive). I would also suggest working out what you want compression wise. In my 308s I have aimed for 10. 5 comp with the knowledge that I'll need 98 fuel, but performance is good from an externally looking stock set up