Why the 318 is a phenomenal engine...
I wish the 318 my Duster came with ran remotely as well as everyone's talking about in here. I don't think the OP is lying either but it's still hard for me to believe. Granted my 318 was quite worn out, lots of bore wear and rings were stuck from carbon build-up but it ran smooth and I was also at 7000' elevation which killed a lot of power. But with the stock cam, 2-bbl and single exhaust it could NOT rev over 4000 RPM while in gear, just completely ran out of breath by that point. After I put reman'd 302 heads on it, Lunati Voodoo 256/262 cam, 625 cfm Carter AFB and dual exhaust off the stock manifolds, then it would pull to about 5500 RPM. 6500 RPM is really really up there for a stock 318.
It was my first engine and in hindsight I should have gotten a healthier short block to swap in but I had no idea how to do things back then I was just getting started in the hobby. I saved that 318 block and crank since they were in good shape, would be fun to build it up one day but once I experienced 360 torque I've had a hard time rationalizing building a 318 unless it's going in a light car with stick-shift, big heads, solid cam and rev to the moon. Like the OP wants to do with his. I just don't have an appropriate vehicle for it lol.