Best Year for Mopar 360 LA Engines

First 360 LA's were built in 71, so you are talking from 71 up to about 1991 or so, I think. This spans a long time obviously.

From 71 to about 76 or so - the 360's were supposed to have used the same casting for the cylinder walls as a 340 - meaning thicker = stronger = better. Later models are supposed to use thinner cylinder walls. I've heard enough about these differences to question the validity of these claims. My preference would be 75 or older (older the better). Ive seen magazine articles about so called thin wall castings from the late 70's, which when checked were as good a piece as the older castings and vice versa, so its a crap shoot. Core shift is the main issue with thicker walled blocks with even or biased core shift towards the thrust side of the cylinders prefered.

Heads on an earlier 360 (71-72) would be the same casting as a 340 - a "J" casting. J's are supposed to be 99% the same as the "famous" 340 X castings, just add 2.02 intake valves and you are there. I would probably not bother with the older iron heads and just go for some eddies or a magnum conversion.

If it were me and I had the choice of building a motor or buying one already built - I'd check the condition of both pieces very carefully. Do you know the owner of the motor, was the work done to your expectations, was it done by a reputable shop ? For a builder (core type) - What is the condition of the block - good, core, junk ? needing everything ? You also need to ask yourself what you want from the motor, race, street, a little of both ? How fast and in what car will it be put in. The questions become diverse when you start looking at these factors.

This should get you started.