But try to get a "modern" instructor; one who knows GPS. IFR is de facto GPS these days. The rest of the stuff one should know, for a backup and to pass the exam
Strange statement to make??
GPS shouldn't be used as a primary means of navigation anyway, so its irrelevant. I would get an instructor that can teach you the ground based navaids properly and use GPS as a backup; En route use of GPS requires additional certification as does using it for approaches.
There are also a limited number of places that use GPS approved approaches, so I would get to grips with ILS, NDB and VOR approaches and leave the GPS stuff until you've passed the skill test as its not a requirement.
TJ