67 dart 360 conversion help!

Sounds like you have a short, fixed yoke 727 that came with the 360. That torque converter will not fit the 904. It will have the weights required for the externally balanced 360.

Chances are the 904 torque converter does not have external balance weights on it. What you neex is a flex ate like this.

https://m.summitracing.com/parts/bmm-10239

With it you can use any neutral (internal) balancex 904 torque converter.

As another point.....if your 360 came with a short 727 it will be out of a truck or motorhome and will have a truck oil pan. You will need a car oil pan and pickup. Same goes for the exhaust manifolds unless you intend to run headers.