For converting a SR20DET (JDM) engine to US Spec valve guides a couple things are needed.

Details:
Order intake and exhaust valves for a SR20DE motor (usually 0.5mm larger)
Order intake guides (bronze) for SR20DE
Order exhaust guides for a Toyota 3E motor
Order a set of valve keepers

Extra Details:
SR20DET OEM intake valve guide dimensions: OD 0.400in ID 6mm
SR20DET OEM exhaust guide dimensions: OD 0.430in ID 7mm

SR20DE USDM intake valve guide dimensions: OD 0.400in ID 6mm
SR20DE USDM exhaust valve guide dimensions: OD 0.400in ID 6mm

You must use the Toyota guides because they are 0.430in OD and 6mm ID. They will allow you to convert the SR20DET head to use parts readily available in the US. Nissan valve seals will not work in this situation because the OD's are different so you must do one of 2 things:

1: Use Toyota 3E valve seals Toyota part# (90913-02066)
2: Machine the top of the guide down to 0.400in OD so that a Nissan SR20DE valve seal will work with the conversion guides

End Result:
SR20DET head that is fully serviceable with US parts.