I had the same problem with the TPS plug not fitting right had to grind a little metal off the elbow adapter and shim the TPS with some washer this is with a 65mm edelbrock throttle body, I have the GT40 tube intake. With the plug not seated right the tsp reading would jump all over the place when the car was running. When I did my 331 stroker this past winter I bought a 70mm Professional Products throttle body they have added a TPS tuner spacer to their throttle bodies which move the tps about 3/8" further out and allows you the ability to rotate the TPS w/o having to take off the IAC and that extra space allows the plug to the tps to go in with out the clearance issue.
I had the same problem with the TPS plug not fitting right had to grind a little metal off the elbow adapter and shim the TPS with some washer this is with a 65mm edelbrock throttle body, I have the GT40 tube intake. With the plug not seated right the tsp reading would jump all over the place when the car was running. When I did my 331 stroker this past winter I bought a 70mm Professional Products throttle body they have added a TSP tuner spacer to their throttle bodies which move the tsp about 3/8" further out and allows you the ability to rotate the TSP w/o having to take off the IAC and that extra space allows the plug to the tsp to go in with out the clearance issue.
I will definately look into their t.b's when i go to replace the stocker, it sure is a cow trying to get in there with a meter, i will have to recheck voltage while its running to make sure its good. It sure was hard to get a good reading in the first place, but I thought it was just due me trying to find the sweet spot in the plug....did the washers at least do the trick afterward, along with the grinding?