Welcome to CHR eboy, ur best bet is to get a pontiac 455, if your goint to put a big block it it. The 231 has no performance potential for the money and, will find an extreme performance diffrence just by bolting up a stock 455 BUT.... there are many performance parts u can buy from www.jegs.com or www.summitracing.com and, include cams, intakes, carbs and a few other things which, would turn that Firebird into a real performer.