Is the 1953 a Powerglide? Those 235s came with full pressure lubrication, aluminum pistons, etc. The sticks were 235 babbit cranks with iron pistons. That engine in the 53 does not look like the original. Does it have the oil distribution plate on the central lower side of the block on the driver's side? That is the sure sign of the babbit pounder engine. Get the block casting numbers for a more positive identification.
You may need the front engine plate from the '49 on either engine to mount it on the front crossmember of the '49. The later engines had side mounts of one type or another, but some of the later plates can attach to the front mounts. See if the front plates on the boneyard engines have the provisions for holding the '49 mounts.
Without seeing the engines, the 1958 seems like a better deal, just for the head. Better condition 235s often go on ebay for not much more than $100.
