727 torque converter question

[65 wagon]

I'm helping a buddy swap out his 727 trans (H2538333 original) that is an 18 Spline that was mated to a 318. The replacement be bought is an 84-85 23 spline PK4329468 that was mated to a 360
My question is, can he simply by a torque converter for the 23 spline 727 & will the hub OD match/fit into the end of the crank - engine side? Some of the archives mention the TC for the 360 engine used weights - externally balanced. What torque converter should we be asking for & if we need to modify or change....what specifically do we need to do?

Thanks in advance,
Benjamin