I don't have Supercomputer numbers for 7-point Trifectas, only the Superfectas (and, thereby, 9-point Trifectas).
My 7-point simulator came out 287 and 321, but it wasn't a long run (160,000).
The Jai-Alai Heaven Tri data came from you, and you said you were in agreement with Lorenzo. Think about it - could be a typo. If necessary, I can try recalculating to see if the cumulative probabilities jibe with the individual row probablities.