Well ya, it's like a teen. How much can you do without building a performance specific engine. With a 273, a 4 barrel will help. so will a distributor curve. (probably the biggest improvement for the lowest dollar invested) A HP single exhaust or a dual system will help. A steeper rear gear won't add horsepower but it will make it spunkier or faster. We all know the next step with the hipo pistons, bigger cam, ported heads, and high stall converter. This has been discussed to death.
