Can i wire my grounds like this(diag inside)

[73GMC10]

Hi guys, sorry about bugging about this , But I just just installed a 350 sbc into my 73 Gmc 2500 4x4 , now I got this engine from a donor truck but all the wiring wasn't there when I was trying to pay attention to things, but the engine was fully complete parts wise,I just want to make sure I have this ground stuff routed correctly. ive looked up and there seems to be several ways to do it but I was hoping for as basic as possible, I always ran my neg cable from the batt to the alt bracket, not sure if this is correct or not

so the way I have it is like this, and feel free to correct me if im wrong or have to add anything.

-3 grounds
-from the batt to the alt bracket
-from the block to the frame
-from the firewall to the bell housing bolt
(also I noticed some have a 16 gauge wire running somewhere,is this needed?)

thanks in advance, I just don't want to have something smoking on me from incorrect wiring.