Oversize valve questions

[Colorado700R]

Stock size exhaust valves will work very well with +1mm intakes that have been mildly ported. A larger intake port with + 1 valves or exh with lower throat percentage will work well with + 1 exh valves. I personally use a smaller throat percentage on the exhaust than some, but I have a very tricky bowl shape. I know your porter has a wet bench, so you need to get with him on your goals and his preferences.
To make any kind of real recommendations that are not just generalizations, we need to know what throat % he likes to run on the intake and exhaust. If you haven't gotten to that point in the planning, just remember that the short turn shape, tulip angle, and valve seat cut angles(and widths of those cuts) go hand in hand.

I would recommend you using + 1 int and exh(to start) to make a good fuel pattern in a stock bore. There are ways to get a better pattern with big valves in the stock bore, but they are either a compromise or complicated. If your guy has the capability of flowing at 40 or 80 in/hg, do it.

Forget about high velocity. You will find out why with higher pressure drops. There are people out there doing high velocity style porting that are flowing air so fast that the fuel separates. Engine failures are not uncommon in these conditions. The only way to really study this is by observing the burn pattern on the piston(and chamber). These suggestions are only geared to the 700 based engine, and they are intentionally vague

  Owww!  Thanks for the brain tumor !!!