Re: A question about a early 400
Hi, yes the early 400C has the smallblock 6 bolt bellhousing pattern. Some also have the 4 small block engine mount bosses but they are not drilled. So it is possible to fit an early 400 in where the smallblock came out. But these blocks are prone to cracking and would be getting hard to find too.
If you were to find one and use it the 289 flywheel will bolt on as the crank bolt poatterns are the same and the balance counterweight is also the same. You would want to upgrade the trans if its not a toploader 4spd as the tq of the 400 will mince the earlier trans in no time.
It is probably going to be a much easier prospect to fit a 351W with a stroker kit. The block is better than the early 400 block, easy to find and easy to get accesories to fit aswell.