That crankshaft almost always needs to be ext balanced or youd have enough $$$ added weight in it you could of bought a steel which almost is always internal. You probably got a great deal on the crank, they are great cranks but many if its gonna take $3-400 in balance metal just goto a steel.
That crank is made by scat and is a good crank, I recently was going to buy one at $300 shipped new but passed because no one I emailed, the sellers of the crank, chicago connection IIRC could not even tell me the bobweight of the crank.
The only way to get that close to internal weight with minimum would of been to use the scat light pro I beam rods and some very very light forged pistons. And then most get a bit of weight. But your passed that now.
When I do have a ext. balance 360 based stroker I got to take everything, including the balancer and flexplate (what converter are you running, a weighted balanced unit or a zero balance and what trans? as some of the B@M flex plates for the 727 wont work on a 904 because they are too big OD because they are drilled for several different diameter converters? And you vert balance also is a factor) I also take the harmonic balancer which for a street motor I use the mid grade that comes with the three different balance weights that bolt in and let the balance shop determine which is best and easy for them to use.
A fully forged kit is the cake walk of balancing as far as effort, simply zero balance everything and the cheapest to balance. (Just drill on the crank)What you are doing is the most complicated but still very doable. You just have 2x things or better things to get in proper order.
What H beam rods are you using? Alot of times the box will have a overall weight and a big and small end weight for a general reference.
You can easily determine what your bobweight will be at home with a few common things and although its always best to let the machine shop guy do it all, you still then have a sheet to compare to because some shops do make mistakes.
And also in your case, any good shop could balance your street stroker, they balance things all the time and most have good equipment and you using good pistons and rods that will be very close if not spot on that they will love because it will be a easy balance job for them, but if you decide to use a race shop thats your choice as well.
Probably not the easy answer you were looking for but in the end you will think to yourself, it wasnt that hard.