The gx160 stock rod is the same rod used in the gx200 and clone 196, 3.303" stock length.
Theres different wrist pin heights when choosing rod piston combos for the 160 and 200/196.
I find it best to measure piston to deck, then chose the rod length to get the piston as close as possible to deck, but not out of it. Then choose a head gasket that will get you close to .030" piston to deck.
There's a light weight flat top piston, and +.080" billet rod combo for the 160.
The 160 needs all the help it can get, lightweight parts don't cost much more then regular parts.
A 160 with .030" piston to deck (head gasket included), flat top piston, and the stock 14cc head will have 10.7:1 CR. This will pull much harder then stock in the entire rpm range.
With a dished piston, will have 9.1: CR. Thats not much more the stock, and IMHO wouldn't be worth building, or adding billet parts to.
This piston with the 6770 rod would be my 1st choice when building a gx160.
https://www.arcracing.com/dj-2195-std-honda-gx160-gx200-t2-piston/