You'll be much happier with the heavier flywheel,though I might not go all the way to 40 lb,I swapped from a stock weight flywheel to a 40 lb aftermarket on my 427 which with the stock wheel was really snappy with throttle response both going up and down with rpm's but with the 40 lb wheel it was much less responsive,I will be going back to the stock weight wheel which is still twice the weight of your aluminum flywheel.The 40 lb flywheel definitely gives the shot out of a cannon sensation but the stock weight wheel pretty much did too.