You could shoot the arrows that you wanted to shoot originally, but you just need to make sure that you don't break that 5 grain/lb. limit. Meaning that for every one pound of draw weight you shoot, your total arrow weight should weight at least 5 grains.
As as example, if you were shooting a 63# shooting weight then your total arrow weight (that includes shaft, insert, tip/broadhead, fletching, nock, etc...) would have to be at least 315 grains at the minimum.
63 X 5 grains = 315 grains total
If you need to shoot a specific arrow length, then you would have to drop your bow's peak weight accordingly. Say if you need to shoot a 26.5" arrow with 85 grain tip. Then it would be figured like this:
arrow shaft at 6.2 GPI would be: 26.5 X 6.2 GPI. = 164.3 grains
tip weight: 85 grains
misc. weight for all other parts (inserts, nock, fletching): approx. 30-40 grains
So, total approximate arrow weight would be:
164.3 + 85 + 40 = 289.3 grains
So, you divide that by the 5 grains per pound and you get:
289.3 / 5 = 57.86# or say 57 pounds max. (even though shooting about 5-10 grains under would be better) or say 55 pounds max.
Just plug in the numbers to get an idea, but it's always a good idea to actually weight your arrows once you get them built, just to know for sure.
Anyway, there are alot of factors that determine the ultimate arrow speed you'll achieve such as your draw length (the longer it is the easier it is to get a fast arrow), total arrow weight, and bow poundage.
Hope that didn't confuse you..