Question on cast crank balancing

Hey guys,

i have a 360 roller motor that i picked up and would like to build as cheaply as possible, thinking that i could reuse the stock cast crank, Eagle SIR rods (on sale at mancini for 99 bucks!) and some forged pistons to get the compression up as well as be able to take some spray in the late future...in all this though, i would really like to get everything internal balanced in case i ever decide to change to an aluminum flywheel, plus my current flywheel is internal balance as well

my question is, would getting the external cast crank balanced to internal require so much mallory metal that im just better off cost wise to buy a brand new internal balance crank? i know mallory metal is expensive, so if it doesnt make sense to do it, i would just buy a new crank...in fact, if im going to buy a new crank, a stroker may be an option, although im not sure if i would need different rods or what the piston selection would be like for the compression ratio id like to achieve...

anyways, before i get even more away from the original question, please share your opinions on this...i know every machine shop charges differently, but im just trying to get a rough idea

thanks!
Matthew