I have replaced conrod but have stuffed up settings. Do not know correct position of piston related to tapped setting

Are you referring to timing marks on the crank and cam? If so you will see small mark on cam that will line up with mark on the crankshaft gear .
Thank you
Don

Ditto. The rest is simple... just put in the valves and springs... its easier if the piston is at top dead center to do this...