Hot Rod 340 builds and dyno test.

Dart 3250# 340 214/224 cam, stock heads, ld340, 750VS, headers, 3.91's 13.30 at 103

And that mph/weight computes to 284flyhp, which again is nowhere near as suggested by that article. Mph does show the hp/weight however it needs to be in synch with the ET as well to show a more accurate hp output. That car@284hp/3250 should be in the 13.13's, get that to ET there and then see if he still pulls 103, would probably lose 1mph which would still make a close hp no.
The issue here for working out hp/weight/mph is when you get a car that really does 60ft like a stocker, an example of that is of a legal A/SAA stocker we have here that runs 9.96@130mph, that normally would be 134>5 for an average brkt car, hp/weight calcs goes out the window there, 9.96 would be 710fhp and the 130mph is just 624fhp against the weight.