Ya know how I hate to be picky, but you are on a path to Nowhere. That's Nowhere, Nada. You are allowing in your mind the un-plan of a bunch of low branches which are going to be nothing more than replacements for the trunks that existed before you chopped. The whole purpose of collecting something and chopping and is to secure for yourself and posterity big low trunks from which you allow and control major branches to grow. You tolerate the big roots in order to get trunks that larger size. By allowing this low, -too low, growth of stuff, you contravene the whole process. Truth is, you chopped too low, eliminating options and now you need to recombobulate your plans and keep picking off buds and twigs that are too low on the trunks, only allowing growth at the tops, and outward facing, and almost nothing in the center of the cluster. That may mean that one or more trunks that will not throw out branches in useful locations, that is: high enough and facing useful airspace be removed completely. Bite the bullet, muy pronto, or eat shit later when the mess is too crowded to get your tools in there. Also, get some light wire and wire all the twigs so they are aimed at the airspace you allow in your plan. Do that very carefully, -they only have to be bent to the right direction. Your plan that you need to scribble on a piece of paper to guide you so you both limit and control what grows because this is very, very crowded and bonsai is two things: controlled growing and making air space for the birdies to fly through. Left to its own devices this will be nothing more than a bush with no definition or character. Sorry to be the bearer of bad news, but better now than too late which is just over the horizon.
