First of all the white wall will not make your red look pink. It just may bleed slightly through, which basically means it needs more coats.
Gray primers are great for allowing you to 2-3 coat a wall so it looks covered. Reds are notorius for needing 5 coats and still looking weak. There is tons of pigment in red paint and it rarely covers. make sure you use Benjamin Moore Regal line (or the top of the line paint) so you can minimize your coats. One coat of medium gray and 2 of Ben Moore should do the trick