I built a 360 many years ago that is in my 4x4.It has flattop w/valve reliefs,zero decked.70cc heads.Iron.Is there a head that has the same chamber size,or close that is closed so I can get good quench?I run 91 octane and have to back my timing off to reduce the ping.Comp cam 268,installed straight up.I would like a bit more grunt to.High gears and 35 in. tall tires.At cruise speeds and with a load if you put your foot in it it will start to ping.