Fact: I bought a frame and crankset from a dude and he threw in a couple spiffy track chains. 1 problem though, they're both way to short, at least 3 links need to be added?

Question: Is there a formula for determining what length chain you need (130mm 3/3242t chainring and a 1/8 16t and 18t cog)?

Question: How did you determine what chain length you needed?

Put the wheel in the dropout so that it is centered and wrap a longer chain around the chain ring and cog to get a chain measurement.

You can bring the wheel forward as long as the nuts do not pass the end of the dropout and with track ends you need to position the wheel about midway so that you can install and remove the wheel and have adequate room to adjust for tension.