If you have verified positively the old converter is a 24 spline my next step would be to see if it's pumping fluid as mentioned earlier. If it is pumping fluid I'd then drop the pan to make sure the manual valve didn't come loose. That's something I haven't seen happen when one is not taken apart but if the shift shaft assy and rooster comb has a lot of slop in it I'd imagine it could happen.
As per your earlier question about checking the numbers on the side of the trans, yes that'd be a good way to identify the trans. Post your number, usually starts with PK, and I'll look it up and see what year it is
One last thing, you mentioned your under the impression the pump circulates in park since you have a Trans-go kit in it. The kit does cause it to circulate some fluid in park but not as much as it does in neutral of any motion gear. If I were checking fluid output I'd still check it in neutral.. JMHO
