Greetings gentlemen. I have a '67 special 2-door sedan that I bought in '01. 300-2 with ST-300. Used it for a daily driver for years. Sold it in '09 and got it back last year. How often does that happen? Now I'm wanting to upgrade the engine. 350, 430, 455, LS? So much to choose from, but I'm on a limited budget. Recommendations? TIA!