Regarding the converter, which Magnum Engine and trans are you using? the 5.2 are neutral balance and the 5.9 Magnum uses a weighted flexplate and a neutral-balanced converter.
The serp belt system on the Magnum will work just fine. If you wanted to change to a V belt and make it look more like an LA, you would need the LA timing cover, water pump and V belt pulley.
Use an LA car style oil pan because the Magnums are truck style and don't fit.
Example -
http://magnummopar.com/kevko-5-2-5-9-magnum-oil-pan/
The cam, if its a 5.2 than the stock cam is almost maxed out, the 5.9 can use the 5.2 cam or a similar regrind.
example -
http://magnummopar.com/camshaft-mil...9l-price-includes-refundable-100-core-charge/
