Can someone please explain what exactly is this?
"Cylinder head was lightly ported with 3 angle valve seats".

Does this requires new valves at a particular angle and then polished and lapped in? or one can make use of the stock valves and modify with 3 angle? and how?

Thanks for your feedbacks

Standard valves can be ground to match a '3 angle' valve seat in the same way needed to fit a standard valve seat, (providing the new valve seat is within standard size limits.)

A 3 angle seat is a normal time-served modification, employed when gas-flowing/porting a cylinder head and is designed to encourage better/faster flow around the valve pocket/seat area than the standard head's valve seating arrangement.

However, many modern multivalve engines already come with this feature, as manufacturers soon realized it's a cheap/easy way to improve the efficiency of their engines.