383 Oil Pump Pickup Question/Problem

We're building a 383 for my son's Dart and have come upon a small problem. The engine has a 187 pan, and we had to buy a replacement oil pump pickup to replace the damaged old one (had been badly gouged by a set of vise grips by whoever put it in last time). Upon trying to install the pan over the pickup we found that the pickup won't screw into the block far enough to allow the pan rails to seat on the block. The threads on the new pickup appear to be about 1/2 inch longer than the old pickup. Now here are my questions:

1) What is the thread size/count on the pickup in case we decide to cut and dress up the threads to make the pickup fit.

2) Do we even have the correct pickup for this combo (383 with 187 pan) ??

Answers, anyone...???

Photo of the new pickup: