A few years ago I started to layout an adapter from the HJ 4 cyl block to a Chev trany. I just took off the bellhousing and block plate and laid it over the template I had previously made and found the starter hole from the 1st engine(1953) is about 1/2" further out than the one I have now, 1951. I will have to check what starter I have on the 51 engine. Also the flexplate from a Chev has the same number of bolts but the bolt circle pattern on the HJ crank is about 1/8 smaller. I filed a pair of holes to get it to fit and will dial indicate it to true it when I get to that stage.