Anyone local to me capable of correcting errors on a 904 race build

I purchased transmission and convertor from a person in the business, and its got 4 neutrals and leaking like a sieve. Less than excited to return it for more problems

I am near Sioux Falls,SD 57107 ..
I have build my own non lockup 904 from a late 80,s lockup.
The first question I have for you is what did you both agree that he was going to build for you.
If I am not mistaken there is a difference in spline count between the lockup and non lockup input shaft.
This will affect your converter choice.
The lockup and non lockup pump each require there respective matching forward clutch as there is a difference in sealing ring diameter of about .060 though. So again, what did you agree he would build for you. You said this is a race 904. To me that means a high stall non lockup converter, and that means a non lockup input shaft from the aftermarket or a slant six trans.
If this trans was being built from a lockup trans into a non lockup to take advantage of the better steel planetaries and 1st gear ratio, requires mixing and matching of input shaft,forward clutch hub,front drum and a custom machined pump to account for the sealing ring diameter difference, and if using a five clutch front drum, needs the bevel machine on the pump to clear the drum.
The easiest way to get a no drive condition
Like you say you have is if the builder used a
Non lockup forward clutch hub with its .060
Smaller diameter, in a lockup pump. The parts will go together, but the sealing ring is the wrong diameter and will result in a huge hydraulic leak and resulting no drive condition. Converting a lockup 904 to a non lockup is not a straight forward rebuild.
It requires parts from two different trans to make one, and there are many pitfalls to watch out for. I am not defending the builder, but it would be easy to make a mistake.
So again what did you agree that he would build for you?

I purchased transmission and convertor from a person in the business, and its got 4 neutrals and leaking like a sieve. Less than excited to return it for more problems

I am near Sioux Falls,SD 57107 ..