Would ya be possible to build a distributor using the shell and cap of the 3.9 and the guts of a V8? I have no idea, I was just thinking about Taco Bell which is causing me to have brain farts.
No two problems.........the points or trigger must match the V6.
Odd or even fire is also a problem, first I knew of this was the old Buick/ Olds/ Jeep 225 V6. The caps....and the breaker points cam...have every other pair closer together........they do not fire every "evenly" 120* of rotation, hence the term "odd fire" or "even fire." So EG you cannot put an even fire distributor into an odd fire engine, or vice-versa.