The '69 318 that you purchased will have the open chamber heads, 9.2:1 cr flat top valve relief pistons. Factory rated at 230 hp.
Just putting a 4 bbl on it even with the stock cam gives them the fuel they need, wakes them up nicely.
As pictured here in this stock '69 Satellite 318.
View attachment 1716024904
Notice the stock cast iron water pump for 1969.
View attachment 1716024905
9.2:1 stock flat top pistons for 1969 that sit .040 ths. down in the hole. Full floating rods too.
View attachment 1716024906