I'm wondering if there is a certain convertor needed to do this or just any ole convertor will work? I'm wanting a simple fun driver and the 518 comes with the engine in a trade.

Disregarding stall, Any Neutral balance SB 727/904/518 convertor will work, it's the flex plate that has to be G3 Hemi specific , ATI , PRW all the usual transmission suspects sell one

I got a TC for the same year I pulled the 518, 95 B3500.
The stall is 2000 for the Van, but the higher torque 5.7 makes it stall ~ 2600.
I couldn't justify paying $800 or more when you can get something from RockAuto for $200.
Search different models, you can get low/med/high stock converters.

Thanks to both of you, I asked the same on a Gen 3 Hemi group on FB over a week ago and haven't had one reply

Quick question with it being a 1991 I presume it isn't a lock up trans.

Look at connector on side, if it has 3 pins, it's lockup.

That I can't not answer with 100% , but I think 91 was the crossover year,

Thanks