but it just sounds so cool

The only idler shaft that contacts the block is the drivers side one (small idler) that comes in contact with the distributor drive gear galley. Yes I bought mine from ebay for $59 You can buy the exact one direct from CAT at their website for $129 if it makes you feel better... The main reason why I recommend the oil slinger is that heat and time eventually takes it's toll on all gaskets/seals and when it does start to wear out the oil slinger will help prevent oil from hemoraging out of the front of your engine after 40,000+ miles down the road. I have found oil slingers in 413 industrial motors with factory timing gears I'm assuming for the utmost in reliability.

I would check the mesh of the gears with the idler buttons out and the gears slid all the way back against the block. If you still have good contact with the gears then use it that way if the gears are too far in and only part of the idler teeth are contacting the cam/crank gears then turn it around. Don't use a cork gasket anywhere unless you want to replace it every 30,000 miles. Cork dries out from the heat and becomes brittle. Paper or composite is the best.