By looking at Leo Santucci book on Chevrolet Inline Six-Cylinder Power Manual on page 2 there is a picture of the 1962 vs 1963 six cylinder motors. Although their length appear to be the same from the pulleys fan belt to the rear of the block, the 1963 does show to be somewhat shorter from the front of the fan blade to the rear of the block. They do not list the lengths of either and do not say how much shorter the 63 is from the 62. The shorter distance looks to come from the water pump pulley itself being somewhat more shallow on the 63 than it is on the 62.

The book does state that the 292 is approximately the same height as the 235, and I assume the 235 is the same heigth as the 216. and the 292 is 19% lighter than the 235.

I guess if needed a guy could put a fan spacer on the 292 and then make it the same length as the 235. (??) But I know you are talking 216 here.

One thing may be of interest is that the picture does show that the 292 has the deep end of the oil pan on the front and the 235 has the deep end of the oil pan on the rear. So this may be something to check out for interference if doing an engine swap.
I don't know where the deep end is at on the 216. (??)

All in all it looks like the 292 would come out being pretty close to the same overall length of the older 216, because of the 216 shorter water pump, but somewhat shorter than the 235.

Just check and see if the oil pan will give you any probloblems.

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Ed