So, I finally got my 383 from my engine builder a couple of weeks ago. Went on vacation for a while, came back and started working on the car.

I was getting ready to install my 9.5" Vigilante torque converter in my beefed up 700R4 transmission when I went to make sure that the mounting holes on the converter lined up with the holes in the flexplate - and of course, they don't. The flexplate I have has what looks like 6 mounting holes and if I try and center the torque converter, the holes are off by about a half inch or so.

I briefly spoke to my engine builder, he said this was a common issue and he typically uses the torque converter as a pattern and just drill the holes. Seems to be the cheapest solution but doesn't sound the best to me. Not sure how much a new replacement flexplate is OR how to make sure to get the right one for my converter/engine...or if if drilling the holes is okay. Please advise.

 

For that, drilling is perfectly OK, if the place you would drill is actually part of the little "pad" feature of your particular flex plate.