5.2 parts interchange

That website seems pretty clear to me

Balancer. Use the balancer that matches the engine.

Flex plate. This I'm not sure, you want a flex for an LA trans? I think you'll need a BM aftermarket flex balanced to the engine (mag) to fit the LA converter. You do NOT want a 360 converter, or knock the weights off.

Engine mounts, mag has 360 type mount ears, use LA mounts

LA pans, 273/318/340 have a large cutout in rear of pan

LA pans 360 has a SMALL cutout in rear. This small cutout is what you want for ALL mags, either 318 or 360