I'll have to do a "write up" some day on my thought process. The short version is: I just preferred factory parts, they were good enough when these cars were built. I will upgrade for durability and extra power. It is easy to go down the rabbit hole of "the best" of anything while you have plenty good enough on hand. I start with the rpm limit of parts ( connecting rods and valve train), say 6,500 rpm. I look at what car I'm working on. I run factory ceramic coated exhaust manifolds and the best factory exhaust. So why do I need 300cfm intake ports running through early 273 exhaust manifolds and 2 1/2 diameter straight through single exhaust? I also drive on the street, sometimes 15 hrs for a couple days with no AC. I'm not going to listen to headers and droning mufflers for any length of time. I've had to floor the Barracuda in panic situations, tires going up in smoke would not have saved me. No 1/4 mile at a time in a controlled environment. No trailer in case of failure.
With the 1.88 intake J heads, the 273 ran like a 340, just a tick slower with a higher rpm. The TQ was mind blowing at the right rpm kick in while still being sweet during normal driving. Non car people would freak if I wound it up to 3,000 rpm and floored it, let alone power shifted at 6,500 rpm. The 170 slant six was really sweet for what it was. You don't even need to gut your early A, you will love it.
