904 behind a Mag

Due to the way my luck is going I need to get my truck back on the road for something to drive while I work on my DD. Been running a 4 speed and then a 3 speed manual behind the 93 Magnum. Due to Bell housing and clutch issues I'm wanting to put the 904 that was behind the la 318 that was in it to the Magnum 318 that's in it now.

From what I have read the 904 torque converter will bolt to the Magnum flex plate if you slightly enlarge one of the holes.

I'm not sure if I still have the Magnum flex plate so my question is will the la flex plate work on the Magnum considering they are both internally balanced.