Nice starter BC to have some fun with.
I wouldn't spend time trying to thicken it - just get another piece of material with good flare/buttressing for that, if that's what you want. Have fun with what you have here first.
For this BC it's not a good time to do any major chopping or profiling. Wait until next Feb-March.
Your current chop site already has some very unfavorable reverse taper due to leaving multiple shoots in that location. Next Spring, re-chop flat just underneath the start of the current reverse taper, wait for your new potential leaders to appear and select one on the front side - eliminate the rest. You will let this new leader grow to 3/4 of the trunk width and then chop it a few inches up - repeat to develop your new apex. A year after your new flat chop if the area has started healing well, you can then perform an angle cut.
@Zach Smith has an awesome BC development guide which would be applicable to your tree.