Odd engine combinations and how did they work.

I had some. First was a 318 shortblock that replaced a 340 short that I broke. I pulled everything off of the 340 including the cam (I detonated some ring lands off the pistons) and stuck it all on the original 100K plus '74 shortblock. Aside from a little loss or power right of idle (4sp E body with 3.23s) there was no difference between the two. That was based on street racing I was doing at the time, not track times. But the car never really fell off.
2nd was a 440 I did for another car. Machined and all new parts. Basically a stock '69 440 with some home ported heads (I was in my teens - so admittedly a bit before I knew very much) and an MP .528 solid. In an E body auto it went 12.1 at 117mph. It was incredibly torquey. That surprised me as it was my first experience with the .528. Well any solid lifter cam to be honest...lol.
A 340 with poor machining and some miles, a top end thrown together with some decent heads and hydraulic Comp cam. Once the car was somewhat debugged it went 12.0s. Horsepower was figured around 460. That surprised me.
A 422 I built for a customer. Still running and with 12K or more on it - by MPH makes about 470hp with the Eagle cast crank (last one I used), gets high teens for gas mileage, runs factory rods an factory ported iron heads.
A 496 more recently built for a customer. Smaller solid flat tappet, ported Stealths, factory exh manifolding an exhaust dyno'd at 450hp at the tires. As he bolts on more speed parts it keeps showing more power. It stil is surprising me...lol.