Not sure if I'm in the right place but here goes
My goal here is a weekend driver, cruiser that's reliable and can be heard more than 10 feet away. I'd also like to get as much power as I can with stock and readily available bolt on parts
Welcome aboard.
Think 5.9 Magnum. Or even a 5.2 Magnum
But if you really want to keep the 273; it takes rpm to make power. Your 273 might power-peak as late as 3800; with a 4bbl and headers perhaps a bit higher.
With an auto trans and say 3.55s, 4000 would be 35mph with 27"tires.
If you cam it, the power peak will move to a higher rpm. Meanwhile the lower rpms will lose power. To overcome that, you will need a higher stall TC. The next bigger cam will move the power peak up about 5% so 37mph. To overcome that, you will need 5% more gear so 3.73s...... but the power peak is still at 35mph. That's not gonna be a whole lotta fun, and it only gets worse after the shift. And if you are stuck with 2.76s fogedabowdit. Those will have to go.
So, If you really want to keep the 273, you can see here that a cam swap is moving the power in the wrong direction. And if you don't cam it, the stock 273 is not gonna show much improvement with headers. The 4bbl is still a good idea, but it also won't accomplish much with the stock cam.
So what is the answer? Well, IMO,TM (Torque Multiplication) is the answer. But it's only good to ~50 mph,after that wind-resistance is gonna slow her down.
Depending on your budget, this might only buy you a TC, and that is where I would start. There is a huge difference in power output of the 273, at 1800 rpm versus at 2800. So for me a Hi-stall is purchase #1.
The second purchase would be rear gears. How much gear to get depends on how much hiway-cruising you are going to want to do. With a stock-273 you are gonna need a lot of rear gear to keep her spinning, otherwise you will measure acceleration with a sundial. Ima thinking 4.30s, but that would be 65=3650rpm with 27s . However, 4.30s compared to 3.23s is 33% more TM off the line. Couple that with say a 2500TC,and you could be looking at 60% to 70% more on-the-road torque at take-off ,and plus 33% after the TC settles down, which could be as early as 18mph. That's half the mph of what the 3.23/1800 combo was doing! Compare the above to; a loss of maybe 5% with the next bigger cam. And this new torque comes at ZERO mph, versus waiting until 35mph.
The penalty of course is cruising comfort.
So,
in conclusion, if the 273 has to stay, I recommend to put your money into a hi-stall TC, AND as much rear gear as you can stand. Then, if you need more power, you are already set up for a modest cam. But realize that power improvements on a stock-273 are rather modest with bolt-ons, and
nothing will compare to the 1-2 punch of stall and gears.
That's AJs two cents worth
