DONT DO IT!
Btw I did what you did and ported on the car and learned why not too. A couple of flakes stuck to the valve stem and gulled up the stem and guide. I would recommend the next set you do is pull them.Check out the Moody Diagram here: https://en.wikipedia.org/wiki/Reynolds_number
Explains a lot about the valve stem sticking out in the flow channel of the port. Sorry... your thread, I get excited, I will be quiet and sit on my hands (squirming).
Im compiling pics now to fully explain the purpose of the design. Give me a little bit. Wichers, youre right. More cfm is vital to rpm production. If the port can not support the demand of the pistons speed during intake...a wall happens. Kinda like sucking through diffrent diameters of straws. Adding a bigger diameter valve actually is a great idea cause the stock valve is beyond shrouded. More like 70% walled! Adding a tad more area would help. The walling around the valve is equally important to why a port injected 2v has adavantages over a port injected 4v. Also note the pi valve cup shape on the face.....VERY IMPORTANT!
The moody diagram is great info! Thanks OLD H2S.