Posible swap for my 273 Barracuda 1966

Cacike said
I readed that in a forum:
ANY Small block 273/318/340/360 small block will fit, but you will need a car oil pan pump and sump from a 63-66 valiant/dart/signet. dont use hi-volume oil pump; it won't fit the pan!
Don't use the wideblock 318, either, won't clear the shock towers. The exhaust manifolds you can use must be off an A body from '63-'71 Headers are near impossible to find.

If this car is a slant six (225) car and you're not changing the K-frame and torsion bars, you are asking for big large gobs of misaligned and body-by-twist-o-flex trouble.

318= poor performance, poor gas mileage.
273 is better, and should be the original for this year...
340 best choice and expensive
360= good performance, externally balanced but problems in early a bodies (63-66) were the weighted flywheel and pulley assemblies will hit the bottom of the radiator support (that sux!).

Most of this is wrong. I ran High volume oil pumps in all my cars with the stock oil pans. Headers can be found, but they are expensive. 64 -66 Barracuda K frames are the same Slant six and 273. Any Small block Mopar will run well and get good gas mileage if set up with a performance cam, intake and 4 barrel carb. Nothing hits the radiator support, you use your pulleys. All small blocks are the same size on the outside. The only thing that is right is: Don't run a 318 Poly Head engine in an early Barracuda. You just need to set a budget, as suggested above and make sure all the parts will work together. I'd get your combination right before I went too far first. Then, if you have the money, you can go as fast as you want.