Torque + Fuel economy

Think of it this way;
The stock slanty makes about what? say 85Net horsepower.
And that brick of a truck needs about 45/50 of em to cruise with at 65mph.
If you do the usual hop-ups to it, and gross it up 50%, to 130Net, Now you still got a slug because that truck is not just a brick, but a heavy brick.
Consider that even a stock smog-era 318 makes more than 130hp.
Now consider the cost to bring the slanty up to 130hp, versus just grabbing a JY 318 with attached transmission.

Or better yet, a 5.2M with a loc-up A999/A998 advertised at 230hpNet. These come already with 9.2 Scr IIRC, or more.

Or best of all, a 5.2M with a loc-up A500/A518 and a 3.91 rearend, out of a JY Dakota. Now you got something for not just Torque and Economy, but it also smokes both tires from take-off, and accelerates to 65, quicker than " we'll get there when we get there."

I mean I don't know the cost of that last one, But I sure as heck wouldn't spend an extra nickle on the slanty over a tune up; starting with a compression test.