I'm with the other that 8.7 N350 will likely be a "hot" load. I run 8.4 N350 at 1.240 OAL behind the MTG 121 IFP's in my Bedell Shorty 38SC and get 1.72 - 1.74 PF.
Relative to your question, the typical "rule of thumb" is a lighter bullet needs more powder (to travel faster) to make the same PF as the heavier bullet. Shape of the bullet, surface area and a myriad of other factors can also influence this "rule of thumb". Therefore using a chrono is the best way to tell what the gun likes.
Good shooting and welcome to Wide Open!