I have some questions;
A stock slanty was about 145crank hp in 1969 right?, later converted to 90Net in the low-compression smog era. Right so far?
OK so;
adding a 2 bbl to the stocker might make a couple of hp at the topend right? so by itself is pretty useless.
adding a freeflow exhaust is the biggest deal with the slanty, giving it a couple to a few ponies starting somewhere around 3000 right,,,,,,,, which is ~33 mph with 2.76s. and a few footpounds along the way.
Adding headers to the stock engine might get you ~10% at peak power, say 3600/42mph again with 2.76s....... and 10% is what again, hyup 9hp..... at 40 mph, and a few footpounds on the way there.
But if you combine the headers and the free-flowing pipes and the 2bbl..... what might you expect? I'm guessing 12hp at 3800/42mph. and how much are you gonna spend on that?
And more importantly; how much performance can you expect, in the area most guys are looking for an increase, namely; off the line and at low-rpm? My guess is ; as good as nothing.
If you want it off the line, forget all that stuff and put a bigger TC in there followed by some bigger gears.
3.55s will put down 28.6% more power right off the line and bring your power peak down to 32mph versus 40. Say your slanty is putting out 100ftlbs(Net) at 1750 the factory stall. After going thru the trans and rear end, and correcting for 25.5" tires to a 12"radius, she would be putting , to the pavement,636 smoking-hot footpounds.
And 3.55s would get her 818. Sweet eh? 818/636= plus 28.6%
To equal that with all the current stuff, the engine would have to put out the same 818 to the pavement with the 2.76s, which would be 100ftlbs x 1.286=128.6 ftlbs(Net) at 1750rpm; good luck with that. You can't do it with the headers and 2bbl. Maybe not even with high compression.You'd probably need to supercharge it
I picked 100ftlbs for ease of math. It doesn't make any difference what numbers I choose because I worked the math as percents.
What about the TC? well at 1750rpm, 100 ft lbs is 33hp. I put 2800s in my slantys; so at 2800 the slanty doesn't make a whole lot more torque. Lets use the same 100ftlbs and we get 53 hp@2800. So
The stocker at 33hp and 2.76s puts down the equivalent of 210hp to the ground.
The stocker with a 2800 and 3.55s puts down the equivalent of 434hp.......... that would be 207%.......... still with 1bbl and single exhaust............ What's the buy-in on that? Well, yur gonna need a suregrip-3.55 and I see one for sale right now on FABO. IIRC;MoparOfficial has it listed.
Two hundred and seven per cent on the start-line, right where the slanty needs it. Then plus 28.6% throughout the rpm range, beginning around 24 mph, and continuing until you shift. And still with the factory 1bbl and horrible exhaust.
So my final question is....... is the earth really a ball?
No-no, I mean what gears do you currently have? If not 2.76s, then the exact same results will be had by adding 28.6% to whatever you do have.