Blackjack:
An aluminum flywheel generally gives you better (quicker) throttle response than a steel unit. On the down side, if you already have an irregular idle due to a lot of cam, an aluminum unit will often aggravate the situation. One thing is for sure, if it is running a stock iron unit, I would get it out as soon as I could.
I know this is not a lot of help, but it will easier to make the decision when you know more about the engine in question. All things being equal, I would go aluminum.
Bud
