If you want to go with a original motor you will have alot of years to pick from,the motors are basicly the same from the late 30s to around 1960,the dodge and plymouth motors are the same and were used in cars untill 1959 and I think in the trucks untill 1960 and maybe a little longer in the power wagon. The chrysler and desoto motors will work but they are a couple of inches longer and the radiator will need to be moved some,if you can find a 53 to 54 dodge with the baby hemi that motor should bolt up,those motors use the flathead six type motor mount in the front and rear of the motor and the six was the standard motor the baby hemi should bolt in the 49 frame. The 49 to 54 chassis were possibly the same and I think the baby hemis came with either a fluid drive or a 3 speed. A local junkyard has quite a few 46 to 52 dodge cars and trucks and plymouths but they have been sitting there a long time. Jeff