Building out a 273 recommendations

You will defiantly have to check out the gears in the diff, My 65 Cuda had 2:93's in it and even with the 4 sp it felt like a dog. I went to 3:23 's and it's like I gained 50 hp. 3:55 would likely be ideal for you. I think the 7 1/4 will hold up for you , as I ran my 340 with the 7 1/4 and only killed the rear with the 14" slicks.

Go with the small cam, (260) TTI headers and duals, and leave the 500 cfm carb. recurve a good electronic ign dist. I think you'll be surprised by the power.